'gvfs sparse' dumps exception to console if '-f' is passed a file that does not exist

Unhandled Exception: System.IO.FileNotFoundException: Could not find file 'M:\testSparse\L#Dirs1.txt'.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
   at System.IO.StreamReader..ctor(String path, Encoding encoding, Boolean detectEncodingFromByteOrderMarks, Int32 bufferSize, Boolean checkHost)
   at System.IO.File.InternalReadAllText(String path, Encoding encoding, Boolean checkHost)
   at GVFS.CommandLine.SparseVerb.Execute(GVFSEnlistment enlistment) in C:\Repos\VFSForGit\src\GVFS\GVFS\CommandLine\SparseVerb.cs:line 154
   at GVFS.Program.<>c.<Main>b__0_4(GVFSVerb verb) in C:\Repos\VFSForGit\src\GVFS\GVFS\Program.cs:line 101
   at CommandLine.ParserResultExtensions.WithParsed[T](ParserResult`1 result, Action`1 action)
   at GVFS.Program.Main(String[] args) in C:\Repos\VFSForGit\src\GVFS\GVFS\Program.cs:line 58

Start at src/GVFS/GVFS/CommandLine/SparseVerb.cs line 154, where the stack trace shows the missing file is read, and inspect how the sparse command handles invalid input. Check the command entry point in src/GVFS/GVFS/Program.cs if needed. Done means a nonexistent file passed with -f no longer produces an unhandled exception dumped to the console.