Ability to disable mangling of errors/warnings

[NikolayMakhonin]

See this file:
node_modules/sapper/dist/core.js

constructor(duration, compiler, sourcemap) {
	this.duration = duration;
	this.sourcemap = sourcemap;

	this.errors = compiler.errors.map(munge_warning_or_error);
	this.warnings = compiler.warnings.map(munge_warning_or_error); // TODO emit this as they happen
	...

function munge_warning_or_error(warning_or_error) {
	return {
		file: warning_or_error.filename,
		message: [warning_or_error.message, warning_or_error.frame].filter(Boolean).join('\n')
	};
}

Can you add option to disable this mangle function. I need full information about errors - with stack trace. For example now I got such error:

✗ client
Cannot read property 'type' of undefined
undefined

It was impossible to find the cause of the error by this text.

[ehrencrona]

Under normal circumstances file and message will already contain file name and the lines around the error, e.g.

  {
    file: 'src/routes/index.svelte',
    message: 'Unused CSS selector\n' +
      '16:   }\n' +
      '17: \n' +
      '18:   img {\n' +
      '      ^\n' +
      '19:     width: 100%;\n' +
      '20:     max-width: 400px;'
  },
  {

So munge_warning_or_error doesn't actually remove any relevant information for these errors.

I guess it's possible to have internal errors of some kind where this information will be missing. Does someone have a way to reproduce an error being reported without sufficient context? The third line (undefined) in the error cited above is presumably the message that is missing from the error.

(I realize a lot of time has passed since the issue was reported)