[4.0.0-beta.2] ReferenceError: fail is not defined

[heikkilamarko]

I migrated my project to use 4.0.0-beta.2. When using extendObservable, I receive the following error:

ReferenceError: fail is not defined

I took a look at the MobX source code and found the possible reason:

In action.ts file, and in the following line:

arg1[arg2] = createAction(name, arg3.value)

name is not defined. Should this be something like:

arg1[arg2] = createAction(arg1.name || "<unnamed action>", arg3.value)

[mweststrate]

Thanks for reporting! Fixed in mobx@4.0.0-beta.3 (this will probably result in some peer dep errors, but you can ignore these)