If FID does not exist, log an error, don't crash.

Problem/Motivation

Follow-up from https://www.drupal.org/project/convert_media_tags_to_markup/issues/30616... ✨ Support for Media Files Postponed: needs info
If ID does not exist, show an error, don't crash.

Steps to reproduce

Use this code:

[[{"fid":"42366","view_mode":"wysiwyg","type":"media","attributes":{"height":180,"width":180,"alt":"Providing Surgical Care to Victims of Violence in Nigeria","class":"media-element file-wysiwyg"}}]]

Proposed resolution

show an error, don't crash.

Remaining tasks

show an error, don't crash, add automated tests.

User interface changes

show an error, don't crash.

API changes

none.

Data model changes

none