message: Allow debug config to return undefined/null
diff: @@ -11,7 +11,7 @@ import { PlatformInformation } from '../platform';
  export class DotnetDebugConfigurationProvider implements vscode.DebugConfigurationProvider {
  constructor(public platformInformation: PlatformInformation) {}
  - public async resolveDebugConfigurationWithSubstitutedVariables(folder: vscode.WorkspaceFolder | undefined, debugConfiguration: vscode.DebugConfiguration, token?: vscode.CancellationToken): Promise<vscode.DebugConfiguration>
  + public async resolveDebugConfigurationWithSubstitutedVariables(folder: vscode.WorkspaceFolder | undefined, debugConfiguration: vscode.DebugConfiguration, token?: vscode.CancellationToken): Promise<vscode.DebugConfiguration | null | undefined>
  {
  if (!debugConfiguration)
  {
  @@ -21,7 +21,7 @@ export class DotnetDebugConfigurationProvider implements vscode.DebugConfigurati
  // Process Id is empty, handle Attach to Process Dialog.
  if (debugConfiguration.request === "attach" && !debugConfiguration.processId && !debugConfiguration.processName)
  {
  - let process: AttachItem = undefined;
  + let process: AttachItem | undefined;
  if (debugConfiguration.pipeTransport)
  {
  process = await RemoteAttachPicker.ShowAttachEntries(debugConfiguration, this.platformInformation);
  @@ -33,7 +33,7 @@ export class DotnetDebugConfigurationProvider implements vscode.DebugConfigurati
  process = await attacher.ShowAttachEntries();
  }
  - if (process)
  + if (process !== undefined)
  {
  debugConfiguration.processId = process.id;
  