Originally reported one of our client, we provided fix but I believe this should be handled ootb by Magnolia:

Story:

Checking logs of live projects, we are maintaining in-house, all of them contains ERRORs 500. Most of them due to wrong links to imaging. There is recognised pattern which has cut original link and adds there dots ... at the end of it. for example:

https://demopublic.magnolia-cms.com/.imaging/mte/travel-demo-theme/1600x1200/dam/tours/flickr-surfer-mandolin-3730...

we are sure these are not generated by our templates but are more probably caused some external indexing robots, pages with links, etc.... and so we can't fix these links.

Anyway in this case of accessing mentioned link above, magnolia throws status 500 error with ugly stack trace.

1. this is heavily spamming the logs
2. shows magnolia's vulnerability for possible attacker

Possible fix:

similarly like 404 page, this piece of code should be added to web.xml:

<error-page>    
<error-code>500</error-code>    
<location>/docroot/500.html</location>  
</error-page>

plus some simple template in docroot itself.

Would be nice if Magnolia has this error handling already build in. Thank you.