[Discussion] Handling of errors

[MatthiasKunnen]

I want to start a discussion about error handling in the TypedJSON.

In my opinion, TypedJSON is too lax regarding default error behavior.

My proposal:

• Errors that arise during non-parsing stage, e.g. type not determinable when using @jsonMember, should always throw and not use the error handler.
  There errors are always the fault of a misconfiguration and I believe there to be no reason why you would ever want to keep that in your code.
• The errorHandler should throw by default. We want to prevent new adopters from bugs silently creeping into their codebase. People that do not mind errors while (de)serializing can overwrite the error handler to go back to the old behavior.

I'd love your opinion @Neos3452.

[Neos3452]

I totally agree with the first point.

For the second, I have mixed feelings. On a frontend, you want to keep going as far as possible. It is not reasonable to error out on a parsing error, and potentially prevent a user from completing a purchase. On the other hand you want to catch such errors as soon as possible — in dev, or in tests. However, from experience silent errors were a real hinderance when undefined randomly cropped into different layers.

[MatthiasKunnen]

Personally, I am a fan of erroring early. Ignoring a problem in an early stage with the hope of things turning out okay almost always causes problems down the line. That being said, I believe we can keep the optimistic behavior available using the custom error handler. People that want the old behavior can use setGlobalConfig({errorHandler: console.error}). I would recommend the default behavior to error, though, for the reasons mentioned point 2 and the silent errors being a hindrance as you said.

Regardless of whether we change the default behavior, both points are a breaking change and will require a new major version.

[MatthiasKunnen]

WIP: master...MatthiasKunnen:error-handling