Rollup Version

3.25.1

Operating System (or Browser)

MacOS

Node Version (if applicable)

16

Link To Reproduction

https://stackblitz.com/edit/rollup-repro-hc1mbx?file=rollup.config.js

Expected Behaviour

When a plugin throws an error with a numeric code, like so:

transform() {
  const error = new Error();
  error.code = 1234;
  throw error;
},

... I would expect this to go through the normal Rollup plugin error reporting process.

Actual Behaviour

An error is thrown from within Rollup itself:

TypeError: error.code.startsWith is not a function

This error comes from this line of code:

...and seems to have been introduced in 23c111c (Rollup v3.25.0).

The assumption seems to be that, if error.code is truthy, then it's a string type. However, a plugin may throw an Error with a numeric type for error.code.