Hi Pieter,
Yes this looks like a bug. Do you have access to the bugs reporting system? If so I would appreciate if you could report an incident to the CA-WDE-DPL-ABP component.
If not, could you please specify some more information?
What is the URL of your Web IDE, is it local version or the cloud version?
Can you please run your Web IDE with this URL parameter sap-ide-debug=true and show the error stack from the browser console when this error appears?
Thanks,
Michal.