Fixes #23756: Insiders can't find existing preLaunchTask

src/vs/workbench/parts/tasks/electron-browser/task.contribution.ts

@@ -893,11 +893,12 @@ class TaskService extends EventEmitter implements ITaskService {
 	}
 
 	private computeWorkspaceTasks(): TPromise<WorkspaceTaskResult> {
+		let configPromise: TPromise<{ config: TaskConfig.ExternalTaskRunnerConfiguration; hasErrors: boolean }>;
+		{
 			let { config, hasParseErrors } = this.getConfiguration();
 			if (hasParseErrors) {
 				return TPromise.as({ taskSet: undefined, hasErrors: true });
 			}
-		let configPromise: TPromise<{ config: TaskConfig.ExternalTaskRunnerConfiguration; hasErrors: boolean }>;
 			if (config) {
 				let engine = TaskConfig.ExecutionEngine.from(config);
 				if (engine === ExecutionEngine.Process && this.hasDetectorSupport(config)) {
@@ -932,13 +933,14 @@ class TaskService extends EventEmitter implements ITaskService {
 					return { config: value.config, hasErrors };
 				});
 			}
-		return configPromise.then((value) => {
+		}
+		return configPromise.then((resolved) => {
 			return ProblemMatcherRegistry.onReady().then(() => {
-				if (!value || !value.config) {
-					return { taskSet: undefined, hasErrors: value !== void 0 ? value.hasErrors : false };
+				if (!resolved || !resolved.config) {
+					return { taskSet: undefined, hasErrors: resolved !== void 0 ? resolved.hasErrors : false };
 				}
 				let problemReporter = new ProblemReporter(this.outputChannel);
-				let parseResult = TaskConfig.parse(config, problemReporter);
+				let parseResult = TaskConfig.parse(resolved.config, problemReporter);
 				let hasErrors = false;
 				if (!parseResult.validationStatus.isOK()) {
 					hasErrors = true;