admin.php:1 Unchecked runtime.lastError: A listener indicated an asynchronous response by returning true, but the message channel closed before a response was received
This error message indicates that there was a problem with the communication between the listener and the message channel. The reason is that sendMessage is now promisified internally, so you can ‘await’ it, but the by-product is that when you don’t specify a callback yourselves, it is added internally anyway in order for the call to return a Promise, which means that since you don’t call sendResponse in onMessage, the API will think that it was you who made a mistake of using a callback and not providing a response, and report it as such.
Since the new behaviour is very confusing for almost everyone, a solution might be to stop showing this error when the callback is not specified, however it might cause confusion for those developers who still use callbacks and forgot to call sendResponse inside onMessage by mistake, which should be reported ideally as it always was.
If you see your extension causing this errors – inspect closely all your onMessage listeners. Some of them probably need to start returning promises (marking them as async should be enough).
If still error showing, try disabled all installed extensions in Chrome then you will get a clear console without errors.
