Error callback not called if specs are not found

[meden]

Describe the bug
Error callback not called if specs are not found.

Expected behavior
The error callback being called even in this case, so to be able to recover.

Minimal reproducible OpenAPI snippet(if possible)
N/A

Screenshots

Additional context
I faced this problem by using a minimal Redoc HTML file, initializing Redoc manually. If the spec URL is wrong, I get a stack trace, and the component dies.

I'd like to be able to re-init the component with the right URL (I'm using a select to switch specs).

I think the issue is because of an uncaught error in a promise, preventing (or better said, not triggring) the callback execution.

Maybe this is related to #1686, or #690 (similar behavior, but different cause).

[AlexVarchuk]

@meden @meden Hi! thanks for bug reporting.
We'll fix that.