nullthrows has either bad condition or bad error message

Hi, while debugging DraftJS, I found out that the function nullthrows checks only for null, but its error message says "Got unexpected null or undefined"

Also, the way its result is typed seems wrong, because undefined passes the condition returning undefined where non-nullable T should be ...

I would expect it to either check also for undefined, or return T | undefined and not return undefined in the error message ...

fbjs/packages/fbjs/src/utils/nullthrows.js

Line 15 in d8f0f43

throw new Error("Got unexpected null or undefined");

I found out that the function nullthrows checks only for null

That's not correct, the function does a != null check which means that null and undefined are both considered not equal to null. If the function instead used !== null then you would be correct.

i just double-checked in the JS console in Chrome to be sure:

null != null
false
undefined != null
false
0 != null
true

I suspect the problem is somewhere else.