Switch to options bag

[mmkal]

Fixes #11

@legendecas since #11 was reopened, I thought why not create a PR to update the proposal itself. Not sure if this process can be quite as simple as this for a Stage 2 proposal (this is one way to find out I guess)!

Note that this also fixes the backwards-compatibility concern with Firefox.

Previously, this proposal could run into trouble if raw strings are thrown. Say you're using a function like:

const foo = () => {
  if (Math.random() < 0.5) {
    throw 'bad luck'
  }
}

Before this change, the proposal would have users do something like:

try {
  foo()
} catch (e) {
  throw new Error('Do something failed!', e)
}

Which in most environments, would create an Error with cause: 'bad luck'. But in Firefox it'd be fileName: 'bad luck'. The suggested usage would now be:

try {
  foo()
} catch (e) {
  throw new Error('Do something failed!', { cause: e })
}

Switching to an options bag will allow Firefox to continue to interpret the second parameter as fileName if it's a string, and an options bag if it's an object (with a cause property).

CC @00ff0000red

[ghost]

Seems like a lot of others would agree,

• What about a better Error spec ? #10 (comment)
• What about a better Error spec ? #10 (comment)
  both mention a cause property.

[legendecas]

Thanks for contribution. LGTM

[hemanth]

Thanks, this adds more clarity!