Document what happens, if API returns an error (e.g. limit exceeded)

Problem/Motivation

Thank you very much for this super helpful and simple module.

Could you maybe add some documentation somewhere in the settings page / module page / README what happens, if the API fails, for example if usage limit is exceeded?

Code-wise it logs an error and returns false. Is the image still generated (but without optimization)?

I think that would be important for non-technical users and can happen, especially when using the free plan.

Thanks!!

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes