Dev.exe is usually used by modders to find problems. "Skip" is great, "skip all" doesn't always work, and "Break" seems "Broken" -doesn't seem to do much. Mostly dev.exe picks up errors in what you edit, which is commonly: GalaxyScenarioDef.galaxyScenarioDef, Gameplay.constants, all entity files, new meshes, buffs, abilities, etc...; anything you edit wrong.
Dev.exe won't always tell you what ability generates an error, so introduce new/modded abilities, buffes, etc... in increments so you have the opportunity to go through a smaller number of files than a larger amount. It throws many strange errors that seem inherently SINS and have nothing to do with what you've done. Star/Clad has sadly chosen to remain completely silent and given no indepth write-up. Be sure to check the txt files in the DEBUG folder -near where your mods install; they might help you fix problems.