Add cross-fork logger for runtime-handler

.changeset/forty-snails-rescue.md

@@ -0,0 +1,5 @@
+---
+'@twilio/runtime-handler': patch
+---
+
+Fix error messages in local development

packages/runtime-handler/src/dev-runtime/internal/crossForkLogger.ts

@@ -0,0 +1,35 @@
+import { LoggerInstance } from '../types';
+
+export class CrossForkLogger implements LoggerInstance {
+  constructor() {}
+
+  debug(msg: string) {
+    this.sendLog('debug', msg);
+  }
+
+  info(msg: string) {
+    this.sendLog('info', msg);
+  }
+
+  warn(msg: string, title: string = '') {
+    this.sendLog('warn', msg, title);
+  }
+
+  error(msg: string, title: string = '') {
+    this.sendLog('error', msg, title);
+  }
+
+  log(msg: string, level: number) {
+    this.sendLog('log', msg, level);
+  }
+
+  private sendLog(level: keyof LoggerInstance, ...args: (string | number)[]) {
+    process.send &&
+      process.send({
+        crossForkLogMessage: {
+          level,
+          args: args,
+        },
+      });
+  }
+}

packages/runtime-handler/src/dev-runtime/internal/functionRunner.ts

@@ -7,6 +7,7 @@ import {
   isTwiml,
 } from '../route';
 import { ServerConfig, Headers } from '../types';
+import { CrossForkLogger } from './crossForkLogger';
 import { Response } from './response';
 import { setRoutes } from './route-cache';
 
@@ -61,12 +62,19 @@ const handleSuccess = (responseObject?: string | number | boolean | object) => {
   }
 };
 
+process.on('uncaughtException', (err, origin) => {
+  if (process.send) {
+    process.send({ err: serializeError(err) });
+  }
+});
+
 process.on(
   'message',
   ({ functionPath, event, config, path }: FunctionRunnerOptions) => {
     try {
       setRoutes(config.routes);
       constructGlobalScope(config);
+      config.logger = new CrossForkLogger();
       let context = constructContext(config, path);
       sendDebugMessage('Context for %s: %p', path, context);
       context = augmentContextWithOptionals(config, context);

packages/runtime-handler/src/dev-runtime/route.ts

@@ -26,7 +26,7 @@ import {
 import { Reply } from './internal/functionRunner';
 import { Response } from './internal/response';
 import * as Runtime from './internal/runtime';
-import { ServerConfig } from './types';
+import { LoggerInstance, ServerConfig } from './types';
 import debug from './utils/debug';
 import { wrapErrorInHtml } from './utils/error-html';
 import { getCodeLocation } from './utils/getCodeLocation';
@@ -303,25 +303,46 @@ export function functionPathToRoute(
         reply,
         debugMessage,
         debugArgs = [],
+        crossForkLogMessage,
       }: {
         err?: Error | number | string;
         reply?: Reply;
         debugMessage?: string;
         debugArgs?: any[];
+        crossForkLogMessage?: {
+          level: keyof LoggerInstance;
+          args: [string] | [string, number] | [string, string];
+        };
       }) => {
         if (debugMessage) {
           log(debugMessage, ...debugArgs);
           return;
         }
+
+        if (crossForkLogMessage) {
+          if (
+            config.logger &&
+            typeof config.logger[crossForkLogMessage.level] === 'function'
+          ) {
+            config.logger[crossForkLogMessage.level](
+              // @ts-ignore
+              ...crossForkLogMessage.args
+            );
+          }
+          return;
+        }
+
         if (err) {
           const error = deserializeError(err);
           handleError(error, req, res, functionPath);
         }
+
         if (reply) {
           res.status(reply.statusCode);
           res.set(reply.headers);
           res.send(reply.body);
         }
+
         forked.kill();
       }
     );