fix: Clone Redis error handlers (#201)

Author: daffl

README.md

@@ -136,7 +136,7 @@ app.configure(
 
 ## How it works
 
-![alt tag](https://raw.githubusercontent.com/PedroMD/feathers-sync/master/feathers-sync%20and%20real-time%20events-60.png)
+![alt tag](https://raw.githubusercontent.com/PedroMD/feathers-sync/master/feathers-sync.png)
 
 ## Caveat: Listening to service events
 
@@ -215,6 +215,6 @@ The `data` for the `sync-in` event should be in the same form as the one that is
 
 ## License
 
-Copyright (c) 2021 Feathers contributors
+Copyright (c) 2025 Feathers contributors
 
 Licensed under the [MIT license](LICENSE).

feathers-sync and real-time events-60.png feathers-sync.pngfeathers-sync and real-time events-60.png renamed to feathers-sync.png

@@ -1,45 +1,60 @@
-const redis = require('redis')
-const debug = require('debug')('feathers-sync:redis')
-const core = require('../core')
+const redis = require("redis");
+const debug = require("debug")("feathers-sync:redis");
+const core = require("../core");
 
-module.exports = config => {
-  return app => {
-    const { key, serialize, deserialize, redisClient, uri } = config
+module.exports = (config) => {
+  return (app) => {
+    const { key, serialize, deserialize, redisClient, uri } = config;
     const options = {
       url: uri,
-      ...config.redisOptions
-    }
+      ...config.redisOptions,
+    };
 
     if (!redisClient) {
-      debug(`Setting up Redis client for ${options.url}`)
+      debug(`Setting up Redis client for ${options.url}`);
     }
 
-    const pub = redisClient || redis.createClient(options)
-    const sub = pub.duplicate()
+    const pub = redisClient || redis.createClient(options);
+    const sub = pub.duplicate();
+    const errorHandlers = pub.listeners("error");
 
-    const msgFromRedisHandler = data => {
-      debug(`Got ${key} message from Redis`)
-      app.emit('sync-in', data)
+    if (errorHandlers.length > 0) {
+      // If error handlers exists, copy them to sub
+      errorHandlers.forEach((handler) => {
+        sub.on("error", handler);
+      });
+    } else {
+      // If not, make sure both pub and sub has an error handler to avoid unhandled rejections
+      const defaultErrorHandler = (err) => {
+        console.error("REDIS ERROR", err);
+      };
+      pub.on("error", defaultErrorHandler);
+      sub.on("error", defaultErrorHandler);
     }
 
-    app.configure(core)
+    const msgFromRedisHandler = (data) => {
+      debug(`Got ${key} message from Redis`);
+      app.emit("sync-in", data);
+    };
+
+    app.configure(core);
     app.sync = {
       deserialize,
       serialize,
       pub,
       sub,
-      type: 'redis',
+      type: "redis",
       ready: new Promise((resolve, reject) => {
-        pub.connect()
-        sub.connect()
-        sub.once('ready', resolve)
-        sub.once('error', reject)
-      }).then(() => sub.subscribe(key, msgFromRedisHandler, true))
-    }
+        pub.connect();
+        sub.connect();
+        sub.once("ready", resolve);
+        sub.once("error", reject);
+      }).then(() => sub.subscribe(key, msgFromRedisHandler, true)),
+    };
 
-    app.on('sync-out', data => {
-      debug(`Publishing key ${key} to Redis`)
-      pub.publish(key, data)
-    })
-  }
-}
+    app.on("sync-out", (data) => {
+      debug(`Publishing key ${key} to Redis`);
+      pub.publish(key, data);
+    });
+  };
+};