Improve fault tolerance for execution of event loops in background threads

[soareschen]

Crate

relayer

Summary of Bug

In the loops of background threads such as ChainRuntime, the loop may break via the ? operator, which short circuits the function and return an error result. When that happens, the current behavior is only to print out an error message.

Such errors should not be ignored and instead should be handled by either:

• Handle the error from some supervisor process that restart the thread.
• Propagate the error to the top level application so that the program is crashed instead of continue operating with errors.

Version

a1e95e1

Acceptance Criteria

Errors in background loops are no longer ignored.

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