build failed, macos 10.13.6, src/MonoDebugSession.cs(11,7): error CS0246: The type or namespace name 'Mono' could not be found

$ which mono
/Library/Frameworks/Mono.framework/Versions/Current/Commands/mono

$ mono --version
Mono JIT compiler version 5.16.0.221 (2018-06/b63e5378e38 Mon Nov 19 18:08:09 EST 2018)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
	TLS:           normal
	SIGSEGV:       altstack
	Notification:  kqueue
	Architecture:  amd64
	Disabled:      none
	Misc:          softdebug 
	Interpreter:   yes
	LLVM:          yes(3.6.0svn-mono-release_60/0b3cb8ac12c)
	GC:            sgen (concurrent by default)

$ npm install
npm WARN deprecated gulp-util@3.0.8: gulp-util is deprecated - replace it, following the guidelines at https://medium.com/gulpjs/gulp-util-ca3b1f9f9ac5
npm WARN deprecated jade@0.26.3: Jade has been renamed to pug, please install the latest version of pug instead of jade
npm WARN deprecated to-iso-string@0.0.2: to-iso-string has been deprecated, use @segment/to-iso-string instead.
npm WARN deprecated minimatch@0.3.0: Please update to minimatch 3.0.2 or higher to avoid a RegExp DoS issue

> mono-debug@0.15.7 postinstall /Users/stephen/dev/vscode-mono-debug
> node ./node_modules/vscode/bin/install

Detected VS Code engine version: ^1.8.0
Found minimal version that qualifies engine range: 1.8.0
Fetching vscode.d.ts from: https://raw.githubusercontent.com/Microsoft/vscode/38746938a4ab94f2f57d9e1309c51fd6fb37553d/src/vs/vscode.d.ts
vscode.d.ts successfully installed!

npm WARN prepublish-on-install As of npm@5, `prepublish` scripts are deprecated.
npm WARN prepublish-on-install Use `prepare` for build steps and `prepublishOnly` for upload-only.
npm WARN prepublish-on-install See the deprecation note in `npm help scripts` for more information.

> mono-debug@0.15.7 prepublish /Users/stephen/dev/vscode-mono-debug
> make build

msbuild /p:Configuration=Release mono-debug.sln
Microsoft (R) Build Engine version 16.0.40-preview+ge6c3a1f9e4 for Mono
Copyright (C) Microsoft Corporation. All rights reserved.

Build started 12/4/2018 2:57:59 AM.
Project "/Users/stephen/dev/vscode-mono-debug/mono-debug.sln" on node 1 (default targets).
ValidateSolutionConfiguration:
  Building solution configuration "Release|Any CPU".
Project "/Users/stephen/dev/vscode-mono-debug/mono-debug.sln" (1) is building "/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj" (2) on node 1 (default targets).
RestorePackages:
  mono --runtime=v4.0.30319 "/Users/stephen/dev/vscode-mono-debug/.nuget/NuGet.exe" install "/Users/stephen/dev/vscode-mono-debug/packages.config" -source ""   -RequireConsent -solutionDir "/Users/stephen/dev/vscode-mono-debug/"
  Restoring NuGet packages...
  To prevent NuGet from downloading packages during build, open the Visual Studio Options dialog, click on the Package Manager node and uncheck 'Allow NuGet to download missing packages'.
  Installing 'ICSharpCode.NRefactory 5.5.1'.
  Successfully installed 'ICSharpCode.NRefactory 5.5.1'.
  Installing 'Mono.Cecil 0.9.6.1'.
  Successfully installed 'Mono.Cecil 0.9.6.1'.
  Installing 'Mono.Debugger.Soft 1.0.20161020.46'.
  Successfully installed 'Mono.Debugger.Soft 1.0.20161020.46'.
  Installing 'Mono.Debugging 1.0.20161020.46'.
  Successfully installed 'Mono.Debugging 1.0.20161020.46'.
  Installing 'Mono.Debugging.Soft 1.0.20161020.46'.
  Successfully installed 'Mono.Debugging.Soft 1.0.20161020.46'.
  Installing 'Newtonsoft.Json 9.0.1'.
  Successfully installed 'Newtonsoft.Json 9.0.1'.
PrepareForBuild:
  Creating directory "bin/Release/".
  Creating directory "obj/Release/".
ResolveAssemblyReferences:
  Primary reference "ICSharpCode.NRefactory".

/Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\ICSharpCode.NRefactory.5.5.1\lib\Net40\ICSharpCode.NRefactory.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
      Resolved file path is "/Users/stephen/dev/vscode-mono-debug/packages\ICSharpCode.NRefactory.5.5.1\lib\Net40\ICSharpCode.NRefactory.dll".
      Reference found at search path location "{HintPathFromItem}".
  Primary reference "ICSharpCode.NRefactory.CSharp".

/Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\ICSharpCode.NRefactory.5.5.1\lib\Net40\ICSharpCode.NRefactory.CSharp.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
      Resolved file path is "/Users/stephen/dev/vscode-mono-debug/packages\ICSharpCode.NRefactory.5.5.1\lib\Net40\ICSharpCode.NRefactory.CSharp.dll".
      Reference found at search path location "{HintPathFromItem}".
  Primary reference "Mono.Cecil".

/Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\Mono.Cecil.0.9.6.1\lib\net45\Mono.Cecil.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
      Resolved file path is "/Users/stephen/dev/vscode-mono-debug/packages\Mono.Cecil.0.9.6.1\lib\net45\Mono.Cecil.dll".
      Reference found at search path location "{HintPathFromItem}".
  Primary reference "Mono.Cecil.Mdb".

/Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\Mono.Cecil.0.9.6.1\lib\net45\Mono.Cecil.Mdb.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
      Resolved file path is "/Users/stephen/dev/vscode-mono-debug/packages\Mono.Cecil.0.9.6.1\lib\net45\Mono.Cecil.Mdb.dll".
      Reference found at search path location "{HintPathFromItem}".
  Primary reference "Mono.Debugger.Soft".

/Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\Mono.Debugger.Soft.1.0.20161020.46\lib\net40\Mono.Debugger.Soft.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
      Resolved file path is "/Users/stephen/dev/vscode-mono-debug/packages\Mono.Debugger.Soft.1.0.20161020.46\lib\net40\Mono.Debugger.Soft.dll".
      Reference found at search path location "{HintPathFromItem}".
  Primary reference "Mono.Debugging.Soft".

/Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\Mono.Debugging.Soft.1.0.20161020.46\lib\net40\Mono.Debugging.Soft.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
      Resolved file path is "/Users/stephen/dev/vscode-mono-debug/packages\Mono.Debugging.Soft.1.0.20161020.46\lib\net40\Mono.Debugging.Soft.dll".
      Reference found at search path location "{HintPathFromItem}".
  Primary reference "Mono.Debugging".

/Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\Mono.Debugging.1.0.20161020.46\lib\net40\Mono.Debugging.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
      Resolved file path is "/Users/stephen/dev/vscode-mono-debug/packages\Mono.Debugging.1.0.20161020.46\lib\net40\Mono.Debugging.dll".
      Reference found at search path location "{HintPathFromItem}".
  Primary reference "Newtonsoft.Json".

/Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\Newtonsoft.Json.9.0.1\lib\net45\Newtonsoft.Json.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
      Resolved file path is "/Users/stephen/dev/vscode-mono-debug/packages\Newtonsoft.Json.9.0.1\lib\net45\Newtonsoft.Json.dll".
      Reference found at search path location "{HintPathFromItem}".

CoreCompile:
  /Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Roslyn/csc.exe /noconfig /nowarn:1701,1702 /nostdlib+ /platform:anycpu32bitpreferred /errorreport:prompt /warn:4 /highentropyva+ /reference:/Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/4.5-api/Microsoft.CSharp.dll /reference:/Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/4.5-api/mscorlib.dll /reference:/Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/4.5-api/System.Core.dll /reference:/Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/4.5-api/System.dll /optimize+ /out:obj/Release/mono-debug.exe /subsystemversion:6.00 /target:exe /utf8output Properties/AssemblyInfo.cs src/MonoDebugSession.cs src/Handles.cs src/Utilities.cs src/DebugSession.cs src/MonoDebug.cs src/Protocol.cs "/var/folders/x6/kq4xq7rx6nz15ys_d9nnd3980000gq/T/.NETFramework,Version=v4.5.AssemblyAttributes.cs"

src/MonoDebugSession.cs(11,7): error CS0246: The type or namespace name 'Mono' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/Utilities.cs(14,7): error CS0246: The type or namespace name 'Mono' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/Protocol.cs(10,7): error CS0246: The type or namespace name 'Newtonsoft' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(830,58): error CS0246: The type or namespace name 'ThreadInfo' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(835,11): error CS0246: The type or namespace name 'ThreadInfo' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(854,35): error CS0246: The type or namespace name 'ObjectValue' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(918,11): error CS0246: The type or namespace name 'ThreadInfo' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(925,11): error CS0246: The type or namespace name 'Backtrace' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(930,11): error CS0246: The type or namespace name 'Mono' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(941,11): error CS0246: The type or namespace name 'ExceptionInfo' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/Protocol.cs(86,4): error CS0246: The type or namespace name 'JsonPropertyAttribute' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/Protocol.cs(86,4): error CS0246: The type or namespace name 'JsonProperty' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/Protocol.cs(86,17): error CS0246: The type or namespace name 'PropertyName' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/Utilities.cs(172,23): error CS0246: The type or namespace name 'ICustomLogger' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(32,11): error CS0246: The type or namespace name 'Mono' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(34,11): error CS0246: The type or namespace name 'ProcessInfo' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(35,11): error CS0246: The type or namespace name 'Mono' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(37,34): error CS0246: The type or namespace name 'BreakEvent' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(38,16): error CS0246: The type or namespace name 'Catchpoint' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(39,11): error CS0246: The type or namespace name 'DebuggerSessionOptions' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(42,19): error CS0246: The type or namespace name 'ObjectValue' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(43,19): error CS0246: The type or namespace name 'Mono' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
src/MonoDebugSession.cs(44,11): error CS0246: The type or namespace name 'ObjectValue' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]

Done Building Project "/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj" (default targets) -- FAILED.
Done Building Project "/Users/stephen/dev/vscode-mono-debug/mono-debug.sln" (default targets) -- FAILED.

Build FAILED.

"/Users/stephen/dev/vscode-mono-debug/mono-debug.sln" (default target) (1) ->
"/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj" (default target) (2) ->
(ResolveAssemblyReferences target) -> 
  /Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\ICSharpCode.NRefactory.5.5.1\lib\Net40\ICSharpCode.NRefactory.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  /Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\ICSharpCode.NRefactory.5.5.1\lib\Net40\ICSharpCode.NRefactory.CSharp.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  /Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\Mono.Cecil.0.9.6.1\lib\net45\Mono.Cecil.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  /Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\Mono.Cecil.0.9.6.1\lib\net45\Mono.Cecil.Mdb.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  /Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\Mono.Debugger.Soft.1.0.20161020.46\lib\net40\Mono.Debugger.Soft.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  /Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\Mono.Debugging.Soft.1.0.20161020.46\lib\net40\Mono.Debugging.Soft.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  /Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\Mono.Debugging.1.0.20161020.46\lib\net40\Mono.Debugging.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  /Library/Frameworks/Mono.framework/Versions/5.16.0/lib/mono/msbuild/15.0/bin/Microsoft.Common.CurrentVersion.targets(2130,5): warning MSB3246: Resolved file has a bad image, no metadata, or is otherwise inaccessible. Could not find file "/Users/stephen/dev/vscode-mono-debug/packages\Newtonsoft.Json.9.0.1\lib\net45\Newtonsoft.Json.dll" [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]


"/Users/stephen/dev/vscode-mono-debug/mono-debug.sln" (default target) (1) ->
"/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj" (default target) (2) ->
(CoreCompile target) -> 
  src/MonoDebugSession.cs(11,7): error CS0246: The type or namespace name 'Mono' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/Utilities.cs(14,7): error CS0246: The type or namespace name 'Mono' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/Protocol.cs(10,7): error CS0246: The type or namespace name 'Newtonsoft' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(830,58): error CS0246: The type or namespace name 'ThreadInfo' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(835,11): error CS0246: The type or namespace name 'ThreadInfo' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(854,35): error CS0246: The type or namespace name 'ObjectValue' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(918,11): error CS0246: The type or namespace name 'ThreadInfo' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(925,11): error CS0246: The type or namespace name 'Backtrace' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(930,11): error CS0246: The type or namespace name 'Mono' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(941,11): error CS0246: The type or namespace name 'ExceptionInfo' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/Protocol.cs(86,4): error CS0246: The type or namespace name 'JsonPropertyAttribute' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/Protocol.cs(86,4): error CS0246: The type or namespace name 'JsonProperty' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/Protocol.cs(86,17): error CS0246: The type or namespace name 'PropertyName' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/Utilities.cs(172,23): error CS0246: The type or namespace name 'ICustomLogger' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(32,11): error CS0246: The type or namespace name 'Mono' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(34,11): error CS0246: The type or namespace name 'ProcessInfo' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(35,11): error CS0246: The type or namespace name 'Mono' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(37,34): error CS0246: The type or namespace name 'BreakEvent' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(38,16): error CS0246: The type or namespace name 'Catchpoint' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(39,11): error CS0246: The type or namespace name 'DebuggerSessionOptions' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(42,19): error CS0246: The type or namespace name 'ObjectValue' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(43,19): error CS0246: The type or namespace name 'Mono' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]
  src/MonoDebugSession.cs(44,11): error CS0246: The type or namespace name 'ObjectValue' could not be found (are you missing a using directive or an assembly reference?) [/Users/stephen/dev/vscode-mono-debug/mono-debug.csproj]

    8 Warning(s)
    23 Error(s)

Time Elapsed 00:00:20.79
make: *** [ONO_DEBUG_RELEASE] Error 1
npm ERR! code ELIFECYCLE
npm ERR! errno 2
npm ERR! mono-debug@0.15.7 prepublish: `make build`
npm ERR! Exit status 2
npm ERR! 
npm ERR! Failed at the mono-debug@0.15.7 prepublish script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/stephen/.npm/_logs/2018-12-04T07_58_20_218Z-debug.log

Start with mono-debug.csproj and packages.config, then reproduce the reported npm install and make build commands on macOS 10.13.6. Check the package-reference warnings alongside src/MonoDebugSession.cs, src/Utilities.cs, and src/Protocol.cs. Done means the dependencies resolve and the Release build completes without the reported missing-type errors.