fromJSON should do runtime type checks

[fenos]

Hi! me again! I can't thank you enough for this piece of art!

I came across an inconsistent behaviour while implementing the Twirp specification.

When using Message.decode(), it throws an error if the data-type is not respected:

TypeError [ERR_INVALID_ARG_TYPE]: The "string" argument must be of type string or an instance of Buffer or ArrayBuffer. Received an instance of Object

Which I believe is the correct behaviour.

However when using the method Method.fromJSON() it tries to cast the parameter instead of checking for the data-type validity as you can see HERE

It could have been great if we could error if the data-type is not respected to mimic the same behaviour and return the exact error in both protocols

What are your suggestions over this?

[fenos]

Right! What I'm after is to have the verify() method that protobuf.js has. Can you guide me on what should be needed to extend the generator to have that embedded?

[fenos]

@stephenh have you had a chance to give this some thoughts?

[stephenh]

@fenos hey, sorry for the delay here; yeah I agree fromJSON should be able to do runtime type-checking (probably all the time, right? I.e. it could be a configuration flag but it seems like a good idea to just always do).

I think my initial implementation was used primarily for internal-to-internal services, so we were pretty trusting of the incoming input, at least in terms of basic things like types/shape.

Are you interested in adding this to fromJSON? Would be great to have a PR.

Thanks!