trim error messages sent to frontend

lib/servers.js

@@ -269,17 +269,22 @@ class ServerRegistration {
   }
 
   filterError (err) {
+    let message = 'Unknown error'
+
     // Attempt to match to the first possible value
     for (const key of ['message', 'description', 'errno']) {
       if (err[key]) {
-        return {
-          message: err[key]
-        }
+        message = err[key]
+        break
       }
     }
-    return {
-      message: 'Unknown error'
+
+    // Trim the message if too long
+    if (message.length > 28) {
+      message = message.substring(0, 28) + '...'
     }
+
+    return message
   }
 }