If the user launches CCS and immediately tries to open a projectless debug by launching a target configuration, they will get a generic "Debug Model Undefined!" error. I hit this immediately after downloading CCS and trying to debug an already built example. I was eventually able to figure out the issue was that no workspace was open yet, so Theia wasn't able to create a launch.json file to auto-populate. 

It'd be nice if CCS prompted you to open / create a workspace when trying to launch a target config without having a workspace open. Alternatively, I think a more descriptive error should be given so it's clear to the user why their debugging session won't start.