Worker process does not recover from Errors

[michaelbromley]

Describe the bug
When a Controller running in the Vendure Worker throws an Error, it thereafter no longer responds to any further WorkerMessages - essentially the worker process is dead even though still running.

To Reproduce
Steps to reproduce the behavior:

1. Create a VendurePlugin with a controller which has a method that throws.
2. Invoke that controller method
3. Observe that no other worker methods will now get executed (e.g. try to re-index the search index)

Expected behavior
The worker process should continue to respond after an Error has been thrown.

Environment (please complete the following information):

• @vendure/core version: 0.7.0
• Nodejs version: 12.4.0
• Database (mysql/postgres etc): any