TypeError: entity_views_field_definition(): Argument #2 ($property_info) must be of type array, null given

RTBC.

Thanks for reporting the issue and contributing a proposed fix.

I haven't seen this issue occur, just commenting as part of going through reported PHP 8.1 compatibility issues. I've only taken a brief glance so my comment should be taken as tentative notes made while passing through.

That said...

The issue appears to be in the data returned by entity_get_all_property_info(). The relevant code in entity_views_field_definition() looks to expect a keyed array for the array $property_info argument. So casting as an array whatever data is returned by entity_get_all_property_info() may mask the error without addressing the root cause.

Suggested next step in debugging: determine what non-array values are being returned as part of the entity_get_all_property_info() return value and debug from there, considering the possibilities that the issue may or may not be in this module.

Hope that's helpful!

-  $title = $title_prefix . $property_info['label'];
+  $title = $title_prefix . (isset($property_info['label']) ? $property_info['label'] : '');

Re this bit, hmm. It looks like it's possible to get back a $property_info array that doesn't have a 'label' key. Is that a valid result? If so, then, yes, this appears to be an appropriate use for the ternary operator.

Since this snippet appears to be constructing a user-facing string, it's not totally clear that the $title_prefix is expected to be valid on its own. This call in entity_views_field_definition() feeds a string that would look odd on its own:

entity_views_field_definition($field . ':' . $nested_key, $nested_property, $table, $title . ' » ');

In that usage, in the case of a missing 'label' key, we might want just the $title without the ' » '. Though whether that's an edge case that's worth addressing at this point....