`toThrowWithMessage` - should assert extra error fields

[razbensimon]

Hey,
I would expect toThrowWithMessage to help with asserting extra/extended Error types. Consider extra fields besides just the error class type and message.

I have this type:

class ExecutionError extends Error {
  exitCode: number;
  failedCommand: string;

  constructor(errorMessage: string, exitCode: number, failedCommand: string) {
    super(errorMessage);
    this.exitCode = exitCode;
    this.failedCommand = failedCommand;
  }
}

which I wish I could assert failedCommand easily in a test.
I tried toStrictEqual too, without luck.

WDYT? Can you add such a thing?
Thanks!