[SDK 51] promise.resolve(null) is throwing NullPointerException in java code about expo

[alanjhughes]

Hi @meteorlxy - You don't need to resolve with null yourself. If you call promise.resolve() without any argument, we will resolve it with null internally. I've pulled your example and doing this works correctly

[lukmccall]

Also, you can cast the null to Object to choose the correct version of the resolve function:

promise.resolve((Object) null);

or

Object result = null;
promise.resolve(result);

It will force the compiler to choose the version that can handle nulls. We will not fix it because the new API was designed to work well with Kotlin, and we don't want to sacrifice anything, either DX or performance, to support all edge cases when interacting with Java. Unfortunately, the behavior you're seeing is not the only one that causes problems when using Kotlin code from Java. If you want to wrap existing Java code with our API, I would advise creating an abstraction layer that wouldn't use primitives from Expo, like promises, when passing data between languages. This gives you the most control.