LateInitializationError when testing

Question

My variable has been initialized but I still get LateInitializationError. I only get this during testing, it works fine normally. Logs:

Closure: () => void from Function 'updateLight':. // This is the value of variable being printed

══╡ EXCEPTION CAUGHT BY GESTURE ╞═══════════════════════════════════════════════════════════════════
The following LateError was thrown while handling a gesture:
LateInitializationError: Field 'updateMethod' has not been initialized.

I can print the variable which is to be used, which means it has been initialized.