Fix #859 Improve the way to handle authorize fn errors in built-in re…

…ceivers

src/App.ts

@@ -55,7 +55,7 @@ import {
   WorkflowStepEdit,
 } from './types';
 import { IncomingEventType, getTypeAndConversation, assertNever } from './helpers';
-import { CodedError, asCodedError, AppInitializationError, MultipleListenerError } from './errors';
+import { CodedError, asCodedError, AppInitializationError, MultipleListenerError, ErrorCode } from './errors';
 // eslint-disable-next-line import/order
 import allSettled = require('promise.allsettled'); // eslint-disable-line @typescript-eslint/no-require-imports
 // eslint-disable-next-line @typescript-eslint/no-require-imports, import/no-commonjs
@@ -692,7 +692,7 @@ export default class App {
     } catch (error) {
       const e = error as any;
       this.logger.warn('Authorization of incoming event did not succeed. No listeners will be called.');
-      e.code = 'slack_bolt_authorization_error';
+      e.code = ErrorCode.AuthorizationError;
       // disabling due to https://github.com/typescript-eslint/typescript-eslint/issues/1277
       // eslint-disable-next-line consistent-return
       return this.handleError(e);
@@ -907,7 +907,7 @@ export default class App {
 }
 
 function defaultErrorHandler(logger: Logger): ErrorHandler {
-  return (error) => {
+  return (error: CodedError) => {
     logger.error(error);
 
     return Promise.reject(error);

src/receivers/ExpressReceiver.ts

@@ -9,7 +9,13 @@ import tsscmp from 'tsscmp';
 import { Logger, ConsoleLogger, LogLevel } from '@slack/logger';
 import { InstallProvider, CallbackOptions, InstallProviderOptions, InstallURLOptions } from '@slack/oauth';
 import App from '../App';
-import { ReceiverAuthenticityError, ReceiverMultipleAckError, ReceiverInconsistentStateError } from '../errors';
+import {
+  ReceiverAuthenticityError,
+  ReceiverMultipleAckError,
+  ReceiverInconsistentStateError,
+  ErrorCode,
+  CodedError,
+} from '../errors';
 import { AnyMiddlewareArgs, Receiver, ReceiverEvent } from '../types';
 import renderHtmlForInstallPath from './render-html-for-install-path';
 
@@ -263,6 +269,17 @@ export default class ExpressReceiver implements Receiver {
         this.logger.debug('stored response sent');
       }
     } catch (err) {
+      const e = err as any;
+      if ('code' in e) {
+        // CodedError has code: string
+        const errorCode = (err as CodedError).code;
+        if (errorCode === ErrorCode.AuthorizationError) {
+          // authorize function threw an exception, which means there is no valid installation data
+          res.status(401).send();
+          isAcknowledged = true;
+          return;
+        }
+      }
       res.status(500).send();
       throw err;
     }

src/receivers/HTTPReceiver.ts

@@ -15,6 +15,7 @@ import {
   ReceiverInconsistentStateError,
   HTTPReceiverDeferredRequestError,
   ErrorCode,
+  CodedError,
 } from '../errors';
 
 // Option keys for tls.createServer() and tls.createSecureContext(), exclusive of those for http.createServer()
@@ -406,6 +407,17 @@ export default class HTTPReceiver implements Receiver {
         }
       } catch (err) {
         const e = err as any;
+        if ('code' in e) {
+          // CodedError has code: string
+          const errorCode = (e as CodedError).code;
+          if (errorCode === ErrorCode.AuthorizationError) {
+            // authorize function threw an exception, which means there is no valid installation data
+            res.writeHead(401);
+            res.end();
+            isAcknowledged = true;
+            return;
+          }
+        }
         this.logger.error('An unhandled error occurred while Bolt processed an event');
         this.logger.debug(`Error details: ${e}, storedResponse: ${storedResponse}`);
         res.writeHead(500);