Debug adapter process has terminated unexpectedly when attach a process.

## Environment data
`dotnet --info` output:
.NET Command Line Tools(1.0.4)
Runtime Environment:
OS Name: macOS Sierra
OS Version: 10.12.5
OS Platform: IOS
VS Code version:1.14.1
C# Extension version:1.12.0-bate3

## Steps to reproduce
1.Create a project with command "dotnet new console -o hwapp" in Terminal.
2.Edit the main function in Program.cs file with following:
while(true)
{
Console.WriteLine("hello world!");//set a bp
}
3.Running the project wihe command"dotnet restore && dotnet run".
4.Open the project named with hwapp in VSCode and Click "yes" to add build and debug.
5.Set a bp in line Console.WriteLine("hello world!") of Program.cs file.
6.Click Debug->.Net Core Attach->processId of hwapp.

## Expected behavior
It will hit breakpoint in line "Console.WriteLine("hello wolrd!")".

## Actual behavior
There is a error with "Debug adapter process has terminated unexpectedly", after about 20 minute, the error changed as following: