Fix ARender search on PDF layers

Steps to reproduce:

• Create a File document with a layered PDF as the main file content. (sample attached).
• From the Annotations tab, add several annotations to the document and wait for autosave.
• Scroll down to a layer containing text.
• Search for a word in the text with the filter "Current page".
  => Search never completes, finds no results.
  => Browser console flooded with error messages (see screenshot)