Renderer::addCacheableDependency(): Argument #1 ($elements) must be of type array, null given

Looks like the trace includes calls within the crossword_pseudofields submodule. I wonder if there's some escape that needs to happen if something is empty?

Based on the issue description created a patch and add check if the filed has no value. Please have a look and review.

Tests are failing. Back to NW.

Patch created with the new approach, Try to fixed the test cases, Please have a look.

The change to CrosswordPseudofieldsFormatter in #8 looks great.

The other changes aren't needed. CrosswordFormatter and CrosswordSolutionFormatter already return an empty array if getEntitiesToView() returns an empty array. Let's undo those changes.

Let me work on #9.

Updated patch as changes suggested in #9.
Please review.