aight so one reason could be corrupted save data. you need to go to your computer's appdata folder, and if on windows, you can press the windows key and the r key at the same time to open a small menu. In said small menu, type in %appdata% and find the FunkinCrew folder. Then delete your save data.
Ik you'll have to redo weekend 1 again but at least you can use the chart editor without it dying again!