[BUG] OpenAPI generation dialog closes without error message on supposedly invalid YAML file

[atextor]

How: List of performed steps
When the OpenAPI generation dialog is used and a custom YAML file is referenced that is invalid in some whay, the dialog closes without any message or hint, instead of displaying information about the problems in the file.

What: Actual result vs expected result
Actual: Dialog closes without message
Expected: Dialog stays open, instead a message about the problem in the file is shown

Where: (e.g. component, version, url, your system info)
AME 5.6.0