[KevinH]

Can't easily be done. Imagine deleting a file during an active file read operation. That is what QtWebengine is facing in PageEdit when you close Sigil. This is not a loss of network situation. The delete can happen just when the page resources are starting to be read from the file. So checking if a file exists is not enough.

And since it is a separate process an on close event handler won't work, and the file reads are being done in separate threads deep inside of QtWebEngine.

I will try to add more file exists checks but deleting any resource as it is being actively loaded is going to still be an issue.