Error handling in async watcher

[rightaway]

Version

2.6.10

Reproduction link

https://jsfiddle.net/anrzf5uh/

Steps to reproduce

Enter 'obj' in the text input and nothing gets printed to console. Enter str in the text input and uncaught exception: message gets printed to console. But it's wrong in both cases.

If you remove async from the watch method and the call to the await method, then it works properly.

Enter 'obj' in the text input and Object { error: "message" } gets printed to console. Enter str in the text input and message gets printed to console. It's right in both cases.

What is expected?

Error handling should work the same in an async watcher as in a sync watcher.

What is actually happening?

Error handling works correctly in a sync watcher but not async watcher.

[posva]

Duplicate of #10009