TypeError: Cannot access offset of type Drupal\Core\StringTranslation\TranslatableMarkup in isset or empty in

The above error occurred when creating a new field.

Can you please clarify what Drupal core version you used and what steps you took when that error happened? From this information, its hard to tell what happened and where. I will need to be able to also get this error to debug it.
Thanks, Alexei.

I see whats happening. You must have encountered the following Drupal core issue: #3475505
Are you using Drupal 11.x-dev perchance? I suspects it can be related to autowiring but will need more info to confirm.

Install the new version of Drupal, enable the field UI, install butils, and use the field UI to create a new field, but the above error is displayed, and the field UI fails to create a new field.

Thank you, confirmed and fixed the issue, created a new release.
Please upgrade to 3.0.8 and confirm the fix.
Regards, Alexei.