Web UI diff view non-functional/blank and error generated

[raymond-rebbeck]

On current latest commit the Web UI diff view on the right-hand side panel is non-functional/blank. There is an error popup with Studio though Edge fails silently with output in the JavaScript console.

Git bisect has indicated that 0d36d4a is the offending commit, appears to have been introduced with PR#424

Error in Studio:

Error in Edge JavaScript console (after opening in VS Code):