I discovered this bug trying to make a function and it ended up locking GDevelop and I had to close without saving.
To reproduce, simply create a custom function like normal. Add a parameter, but don’t enter a parameter name. Then, add a second one the same way. Now click on the first or second parameter name, and then click on the other one. At this point, Gdevelop will show you a popup window saying that you must enter a parameter name. Closing it will reopen it again. You will be unable to interact with Gdevelop from here.
Here is a picture:
Hoping this gets fixed, it didn’t cause too many problems for me but it was a pain never-the-less.