Add type check for eventProxy function

[AkeemMcLennon]

Very that event proxy callback function is actually a function

[developit]

Hi Akeem,

Any context for this PR? I had left out the type check in order to show an error when the handler was the wrong type. Though I guess the error would be a bit useless ("cannot call method call of undefined"). Seems like it would be worth showing some form of error though? Interested to hear your thoughts.

[AkeemMcLennon]

Hi @developit, this really goes in conjunction with developit/preact-markup#3

When I wrote a test for the negative case where the allow-events weren't enabled, I got the undefined error.

However, I'm fine with throwing an Error / Exception instead if that's what you'd prefer.

[developit]

Ah, excellent, that's what I was looking for. I'm going to check if there is a way to throw a more useful error here, will let you know. Part of an ongoing effort to provide a better debugging experience, but retain the dev <-> prod parity, instead of requiring that people switch builds or apply globals to get suitably production-worthy builds.

[AkeemMcLennon]

Updated to throw an Error now

[developit]

I think we might be able to combine this with #153. If it can cover all the cases for event handlers, need add more tests and look at compat, then I believe the TypeError would be similar to this one. Will keep you posted as I merge these on Thursday/Friday (sorry for vacation delays!).

[developit]

Hey Akeem - I'm going to close this one out since the work for #153 ended up throwing a TypeError here for non-function handlers. Thanks so much for your work!!