If you are trying to access the debugger, and your application crashes before it can open the debugger window, there probably was an expression that was entered into the Expression pane of the debugger that overloads the application. Thus, the application would crash before being able to open the debugger.

To fix this, hold down the SHIFT key right before opening the debugger. This will clear all expressions in the Expression pane and reset it. Then, the debugger should open normally. Remember to click the save icon so that the expression does not return, or else you would need to hold down SHIFT every time: