Adding a null check for the $paragraph_entity

[nchiasson-dgi]

GitHub Issue: N/A

What does this Pull Request do?

The $paragraph_entity variable could be set as null and then immediately have a member function attempt to be called on it, resulting in the following error:

Fatal error: Uncaught Error: Call to a member function hasField() on null in /path/to/files/controlled_access_terms/src/Plugin/search_api/processor/EDTFYear.php:254

What's new?

Adding a null check for the $paragraph_entity.

• Does this change require documentation to be updated? No.
• Does this change add any new dependencies? No.
• Does this change require any other modifications to be made to the repository
  (i.e. Regeneration activity, etc.)? No.
• Could this change impact execution of existing code? Yes.

How should this be tested?

Enabling the EDTF Year processor and indexing the edtf_year field.

Interested parties

@Islandora/committers