Problem with mutationfn in usemutation hook

I am in the middle of intermediate class and have problem with mutation process however I just follow the video step by step. I code from the beginning several times and every time I face this error.

The Error:
No overload matches this call.
The last overload gave the following error.
Object literal may only specify known properties, and ‘mutationFn’ does not exist in type ‘readonly unknown’.ts(2769)
useMutation.d.ts(6, 25): The last overload is declared here.
(property) mutationFn?: MutationFunction<unknown, void> | undefined

Does anyone know how should I solve it?
Thanks

You probably need to add “return” at the start of line 10