fix: show a nice error message when requesting async stacks

Fixes #353

Author: connor4312

src/adapter/stackTrace.ts

@@ -10,6 +10,7 @@ import { IPreferredUiLocation } from './sources';
 import { RawLocation, Thread } from './threads';
 import { IExtraProperty, IScopeRef } from './variables';
 import { LogPointCompiler } from './breakpoints/conditions/logPoint';
+import { asyncScopesNotAvailable, ProtocolError } from '../dap/errors';
 
 const localize = nls.loadMessageBundle();
 
@@ -184,7 +185,9 @@ export class StackFrame {
   }
 
   async scopes(): Promise<Dap.ScopesResult> {
-    if (!this._scope) return { scopes: [] };
+    if (!this._scope) {
+      throw new ProtocolError(asyncScopesNotAvailable());
+    }
 
     const scopes: Dap.Scope[] = [];
     for (let scopeNumber = 0; scopeNumber < this._scope.chain.length; scopeNumber++) {

src/dap/connection.ts

@@ -183,7 +183,6 @@ export default class Connection {
           Number(process.hrtime.bigint() - receivedTime) / 1e6,
         );
       } catch (e) {
-        console.error(e);
         const format = isExternalError(e)
           ? e.message
           : `Error processing ${msg.command}: ${e.stack || e.message}`;
@@ -195,6 +194,7 @@ export default class Connection {
             body: { error: e.cause },
           });
         } else {
+          console.error(e);
           this._send({
             ...response,
             success: false,

src/dap/errors.ts

@@ -19,6 +19,7 @@ export const enum ErrorCodes {
   InvalidHitCondition,
   InvalidLogPointBreakpointSyntax,
   BrowserNotFound,
+  AsyncScopesNotAvailable,
 }
 
 export function reportToConsole(dap: Dap.Api, error: string) {
@@ -28,11 +29,11 @@ export function reportToConsole(dap: Dap.Api, error: string) {
   });
 }
 
-export function createSilentError(text: string): Dap.Error {
+export function createSilentError(text: string, code = ErrorCodes.SilentError): Dap.Error {
   return {
     __errorMarker: true,
     error: {
-      id: ErrorCodes.SilentError,
+      id: code,
       format: text,
       showUser: false,
     },
@@ -147,6 +148,15 @@ export const browserNotFound = (
 export const invalidLogPointSyntax = (error: string) =>
   createUserError(error, ErrorCodes.InvalidLogPointBreakpointSyntax);
 
+export const asyncScopesNotAvailable = () =>
+  createSilentError(
+    localize(
+      'asyncScopesNotAvailable',
+      'Variables not available in async stacks',
+      ErrorCodes.AsyncScopesNotAvailable,
+    ),
+  );
+
 export class ProtocolError extends Error {
   public readonly cause: Dap.Message;
 

src/test/logger.ts

@@ -161,23 +161,27 @@ export class Logger {
       );
       if (!withScopes) continue;
       const scopes = await this._dap.scopes({ frameId: frame.id });
-      for (let i = 0; i < scopes.scopes.length; i++) {
-        const scope = scopes.scopes[i];
-        if (scope.expensive) {
-          this._log(`  scope #${i}: ${scope.name} [expensive]`);
-          continue;
+      if (typeof scopes === 'string') {
+        this._log(`  scope error: ${scopes}`);
+      } else {
+        for (let i = 0; i < scopes.scopes.length; i++) {
+          const scope = scopes.scopes[i];
+          if (scope.expensive) {
+            this._log(`  scope #${i}: ${scope.name} [expensive]`);
+            continue;
+          }
+          await this.logVariable(
+            {
+              name: 'scope #' + i,
+              value: scope.name,
+              variablesReference: scope.variablesReference,
+              namedVariables: scope.namedVariables,
+              indexedVariables: scope.indexedVariables,
+            },
+            {},
+            '  ',
+          );
         }
-        await this.logVariable(
-          {
-            name: 'scope #' + i,
-            value: scope.name,
-            variablesReference: scope.variablesReference,
-            namedVariables: scope.namedVariables,
-            indexedVariables: scope.indexedVariables,
-          },
-          {},
-          '  ',
-        );
       }
     }
 

src/test/stacks/stacks-async.txt

@@ -13,8 +13,12 @@ bar @ <eval>/VM<xx>:13:15
 
 ----async function----
 <anonymous> @ <eval>/VM<xx>:8:11
+  scope error: Variables not available in async stacks
 ----setTimeout----
 foo @ <eval>/VM<xx>:7:9
+  scope error: Variables not available in async stacks
 bar @ <eval>/VM<xx>:13:15
+  scope error: Variables not available in async stacks
 ----async function----
 <anonymous> @ <eval>/VM<xx>:15:7
+  scope error: Variables not available in async stacks

src/test/stacks/stacks-cross-target.txt

@@ -7,5 +7,7 @@
 
 ----postMessage----
 <anonymous> @ ${workspaceFolder}/web/worker.js:6:5
+  scope error: Variables not available in async stacks
 ----Worker.postMessage----
 <anonymous> @ <eval>/VM<xx>:1:10
+  scope error: Variables not available in async stacks