This crash caused me a major headache today when a new content type went live on our production system. Our editor tried to import pages from the stage system; they imported successfully but crashed when he tried to open them to edit.
Turned out that the image field in the content type had been configured without a preview image style selected, and was defaulting to "thumbnail", which doesn't exist, and was then causing this crash.
This raises two questions for me:
Firstly, why does the image style default to a style that doesn't exist? If the style doesn't exist, don't use it as a default.
And secondly, why is a crash like this allowed to persist in core? It's a relatively easy crash to make happen, and easy to fix (the patch is already done ages ago), and the crash message itself doesn't include the key detail of what image style is causing the problem, which makes it much harder to diagnose.
Please can this patch get reviewed and pushed into the next release. Thank you. :)
Spudley → created an issue.