debug: always use the first configuration even if none is chosen

fixes #14403

src/vs/workbench/parts/debug/common/debug.ts

@@ -338,9 +338,24 @@ export interface IRawBreakpointContribution {
 }
 
 export interface IConfigurationManager {
+
+	/**
+	 * Returns a resolved debug configuration.
+	 * If nameOrConfig is null resolves the first configuration and returns it.
+	 */
 	getConfiguration(nameOrConfig: string | IConfig): TPromise<IConfig>;
+
+	/**
+	 * Opens the launch.json file
+	 */
 	openConfigFile(sideBySide: boolean): TPromise<boolean>;
+
+	// TODO@Isidor remove this from the interface
 	loadLaunchConfig(): TPromise<IGlobalConfig>;
+
+	/**
+	 * Returns true if breakpoints can be set for a given editor model. Depends on mode.
+	 */
 	canSetBreakpointsIn(model: editor.IModel): boolean;
 }
 

src/vs/workbench/parts/debug/electron-browser/debugService.ts

@@ -111,7 +111,7 @@ export class DebugService implements debug.IDebugService {
 		this.model = new model.Model(this.loadBreakpoints(), this.storageService.getBoolean(DEBUG_BREAKPOINTS_ACTIVATED_KEY, StorageScope.WORKSPACE, true), this.loadFunctionBreakpoints(),
 			this.loadExceptionBreakpoints(), this.loadWatchExpressions());
 		this.toDispose.push(this.model);
-		this.viewModel = new viewmodel.ViewModel(this.storageService.get(DEBUG_SELECTED_CONFIG_NAME_KEY, StorageScope.WORKSPACE, 'null'));
+		this.viewModel = new viewmodel.ViewModel(this.storageService.get(DEBUG_SELECTED_CONFIG_NAME_KEY, StorageScope.WORKSPACE, null));
 
 		this.registerListeners(eventService, lifecycleService);
 	}

src/vs/workbench/parts/debug/node/debugConfigurationManager.ts

@@ -261,9 +261,10 @@ export class ConfigurationManager implements debug.IConfigurationManager {
 					return result;
 				}
 				// if the configuration name is not set yet, take the first launch config (can happen if debug viewlet has not been opened yet).
-				const filtered = nameOrConfig ? config.configurations.filter(cfg => cfg.name === nameOrConfig) : [config.configurations[0]];
+				const filtered = config.configurations.filter(cfg => cfg.name === nameOrConfig);
 
-				result = filtered.length === 1 ? objects.deepClone(filtered[0]) : null;
+				result = filtered.length === 1 ? filtered[0] : config.configurations[0];
+				result = objects.deepClone(result);
 				if (config && result) {
 					result.debugServer = config.debugServer;
 				}