ERROR [2019-08-14 00:15:27Z]: An unhandled exception has occurred. Terminating Visual Studio? False
System.ArgumentNullException: Value cannot be null.
Parameter name: path2
  at System.IO.Path.Combine (System.String path1, System.String path2) [0x000a0] in /Users/builder/jenkins/workspace/build-package-osx-mono/2019-06/external/bockbuild/builds/mono-x64/mcs/class/corlib/System.IO/Path.cs:127 
  at System.IO.FileSystemEventArgs.get_FullPath () [0x00000] in /Users/builder/jenkins/workspace/build-package-osx-mono/2019-06/external/bockbuild/builds/mono-x64/mcs/class/System/System.IO/FileSystemEventArgs.cs:66 
  at MonoDevelop.Projects.FileWatcherWrapper.OnFileDeleted (System.Object sender, System.IO.FileSystemEventArgs e) [0x00000] in /Users/vsts/agent/2.155.1/work/1/s/monodevelop/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/FileWatcherService.cs:283 
  at System.IO.FileSystemWatcher.RaiseEvent (System.Delegate ev, System.EventArgs arg, System.IO.FileSystemWatcher+EventType evtype) [0x00060] in /Users/builder/jenkins/workspace/build-package-osx-mono/2019-06/external/bockbuild/builds/mono-x64/mcs/class/System/System.IO/FileSystemWatcher.cs:438 
  at System.IO.FileSystemWatcher.OnDeleted (System.IO.FileSystemEventArgs e) [0x00000] in /Users/builder/jenkins/workspace/build-package-osx-mono/2019-06/external/bockbuild/builds/mono-x64/mcs/class/System/System.IO/FileSystemWatcher.cs:460 
  at System.IO.FileSystemWatcher+<>c__DisplayClass70_0.<DispatchEvents>b__1 () [0x00000] in /Users/builder/jenkins/workspace/build-package-osx-mono/2019-06/external/bockbuild/builds/mono-x64/mcs/class/System/System.IO/FileSystemWatcher.cs:524 
  at System.Threading.Tasks.Task.InnerInvoke () [0x0000f] in /Users/builder/jenkins/workspace/build-package-osx-mono/2019-06/external/bockbuild/builds/mono-x64/external/corert/src/System.Private.CoreLib/src/System/Threading/Tasks/Task.cs:2476 
  at System.Threading.Tasks.Task.Execute () [0x00000] in /Users/builder/jenkins/workspace/build-package-osx-mono/2019-06/external/bockbuild/builds/mono-x64/external/corert/src/System.Private.CoreLib/src/System/Threading/Tasks/Task.cs:2319 

Please paste the stack trace here if available.