According to the uber-handy Makecode Documentation
Panic codes
Some panic codes are for general errors that might occur while your program runs. Other times, a device or resource you want to use isn’t present or isn’t working and you receive a panic code for that. Several panic codes are related to the use of memory and accessing data in it.
- 980 (
PANIC_CAST_FROM_UNDEFINED): attempted cast from anundefinedvalue to another type
A 980 error usually occurs when something related to using undefined goes wrong.
This topic also covers a 980 error.
I’m not sure how much I can help considering I don’t speak French (perhaps @YuHayate could help with that?). Try using the debugger until you run into the error again. It should give some more useful information