Is there any way to access webkit JavaScript and HTTP errors that happen when capturing a page with CutyCapt? I'm trying to debug a thumbnail capture for JavaScript generated documents.
This is not currently possible. I would recommend using a tool like Wireshark to debug any HTTP errors that might occur. It would be easy to add tracing code for network replies to CutyCapt and there are some patches on SourceForge and/or GitHub that do that. I am not sure what could be done to trace JavaScript errors, but ordinarily there should not be any that do not also occur when a page is loaded in a browser. Qt comes with a sample application that implements a rudimentary web browser that could be used for this purpose. I think it also comes with the standard debugger, but I might be misremembering that.