Add Error.cause to all Deno.errors instances about deno

[oles]

I see, I may be thinking about this wrong.

I'd like to see what caused the error, as I think the ConnectionRefused is too vague. Perhaps it's better to add some details to it instead.

The more I think about it, the more it makes sense for Postgres.js to instead add a cause to its error(s) and wrap the ConnectionRefused 🤔

[bartlomieju]

@oles I'm still not sure how that would work - the error you see above is an instance of Deno.errors.ConnectionRefused. The way it is constructed is that when a relevant native (Rust) API raises it, it's translated to that instance. There's no underlying "cause" or other error that could be "linked".

I think I'm missing a point here, so any further explanation would be helpful 😅

[bartlomieju]

What would the cause be set it?

[oles]

Based on the stack trace, I think it should be the cachedError - the error just before ConnectionRefused is thrown - but I'm not fully sure.

I've at least written code before that was similar to the currently first MDN example, which would result in what I think - it seems.

try {
  connectToDatabase();
} catch (err) {
  throw new Error("Connecting to database failed.", { cause: err });
}

[bartlomieju]

Sorry I'm a bit confused here. Is this issue about adding cause field to all instance of Deno.errors.* classes? Or is it about the fact that if you pass one of these instances to { cause: err} it doesn't work properly?

[oles]

Sorry for the confusion! I could likely have been clearer.

Adding a cause field to all instances of the Deno.errors.* is what I mean, yes :)