Testing and fixing bugs are part of a normal development cycle. I created a diagram of BSA itself for testing and as it re-loaded it looked good.
I then moved BSASymbol and got a shock as several of the lines was linked to an invisible ghost symbol. The original lines was from the save, but as I move an object it recalculates every line and voila.
Bug fixing is usually 99% understanding how and why and 1% fixing it. The fix in this case was 3 lines of code and 3 days of tracking down the error. This is a developers life regardless what you develop in. Some of my worst bugs was on embedded code and it took us a good 2-3 weeks to track it down. Luckily it is seldom I have bugs on this level, but this is why we need testing.
At the end of the day the project is saved in very readable XML that can be opened in a text editor and fixed manually in case the tool actually screws up work.