No warning if constant is null or handler is missing

[jhollingworth]

This code will produce the unhelpful error "TypeError: Cannot read property 'isActionCreator' of null "

var FooStore = Marty.createStore({
  handlers: {
    bar: null
  },
  bar() {
  }
});

and this code will cause the page to render nothing

var BarStore = Marty.createStore({
  handlers: {
    bar: "BAR"
  }
});

This is a regression as there used to be useful warnings for it

[taion]

I took a quick look here. Some interesting things going on.

The null issue happens for an interesting reason. The current store implementation only validates the handlers in handleActions, so you don't even potentially get the warning until the first time something gets dispatched (rather than on store creation... but you can't really check on store creation because the base class constructor is invoked first, and handlers isn't currently static).

Then there's another interesting thing going on with

_.once(() => validateHandlers(this))

where as implemented, _.once really only does run that function once, even if it throws, and if it does throw, it will just keep returning undefined whenever you call it, which means that you only throw the ActionPredicateUndefinedError the first time, but then pass right through validateHandlers on subsequent calls, which gets you to the isActionCreator error.

The last wrinkle is that, because of the validation only getting invoked on action handling, if you have code that looks like the example here: http://martyjs.org/guides/queries/index.html, that catch will actually catch the exception thrown from this.dispatch, which then won't necessarily get logged out. Without it, the ActionPredicateUndefinedError does get logged (the first time, subsequent times log the error on isActionCreator).

[sporto]

I had an action with:

    this.dispatch(constants.NOTES_UPDATED, data);

NOTES_UPDATED was undefined. Marty would happily try to dispatch this. I would probably expect to see an error telling me that NOTES_UPDATED is undefined.

[jhollingworth]

@sporto good point, I've just added a check for that