It crashes on the startup. How can I fix that?
<- no Pro, but
You may could try it, like in another game it was described with a mod:
Save your save-files folder first at another place if you would like to use them again.
Delete the game folder within the Renpy-Folder ( C:\Users\(your PC name)\AppData\Roaming\RenPy )
Delete the installation folder ( Drive:\(installation Path)\(installation Path)\ BaDIK )
Install new
*Now thats the point*
Once start the .exe and leave at start window.
(This will install all basic necessary folders and data files on your drive, e.g. the RenPy folder for the game again)
Thereafter, install your mod(s) in given folders and overwrite, when asked ( atm unsure about it but the scrappy mod does not overwrite anything).
Now, you could transfer your save-files again to new given save-folder...
The save-files in your game-folder are sufficient to save at another location and copy back. The Renpy-Folder with save will be overwritten with it.