Merge branch '41468-error-500-trying-to-view-a-merge-request-json-undefined-method-binary-for-nil-nilclass' into 'master'

Resolve "Error 500 trying to view a merge request JSON: undefined method `binary?' for nil:NilClass"

Closes #41468

See merge request gitlab-org/gitlab-ce!16193

(cherry picked from commit 016a2b6e)

528b5eeb Fix error when viewing diffs without blobs