Don't crash when there is no main script

Author: Paul van Brenk

Nodejs/Product/Nodejs/Workspace/ContextMenuProvider.cs

@@ -11,10 +11,12 @@
 using Microsoft.NodejsTools.NpmUI;
 using Microsoft.VisualStudio;
 using Microsoft.VisualStudio.OLE.Interop;
+using Microsoft.VisualStudio.Shell;
 using Microsoft.VisualStudio.Workspace;
 using Microsoft.VisualStudio.Workspace.Debug;
 using Microsoft.VisualStudio.Workspace.VSIntegration.UI;
 using Microsoft.VisualStudioTools.Project;
+using ShellInterop = Microsoft.VisualStudio.Shell.Interop;
 
 namespace Microsoft.NodejsTools.Workspace
 {
@@ -166,6 +168,11 @@ private async void ExecDebugAsync(WorkspaceVisualNodeBase node)
                 var workspace = node.Workspace;
                 var packageJson = PackageJsonFactory.Create(((IFileNode)node).FullPath);
 
+                if (string.IsNullOrEmpty(packageJson.Main))
+                {
+                    return;
+                }
+
                 //invoke debuglaunchtargetprovider on this file
                 var fileContextActions = await node.Workspace.GetFileContextActionsAsync(packageJson.Main, new[] { DebugLaunchActionContext.ContextTypeGuid });
                 if (fileContextActions.Any())

Nodejs/Product/Nodejs/Workspace/PackageJsonScannerFactory.cs

@@ -43,13 +43,16 @@ protected override Task<List<FileReferenceInfo>> ComputeFileReferencesAsync(stri
 
                 var packageJson = PackageJsonFactory.Create(filePath);
                 var main = packageJson.Main;
-                var fileReferences = new List<FileReferenceInfo>
+
+                var fileReferences = new List<FileReferenceInfo>();
+
+                if (!string.IsNullOrEmpty(main))
                 {
-                    new FileReferenceInfo(main,
-                    context: "Debug",
-                    target: main,
-                    referenceType: (int)FileReferenceInfoType.Output)
-                };
+                    fileReferences.Add(new FileReferenceInfo(main,
+                        context: "Debug",
+                        target: main,
+                        referenceType: (int)FileReferenceInfoType.Output));
+                }
 
                 return Task.FromResult(fileReferences);
             }