Expose ssrRewriteStacktrace

[Rich-Harris]

Clear and concise description of the problem

In SvelteKit, stack traces are rendered in dev mode on error pages for errors encountered during SSR. These errors could be expected...

export function load() {
  return {
    status: 400,
    error: new Error('This error was expected')
  };
}

...or unexpected:

export function load() {
  throw new Error('This error was unexpected');
}

In the latter case, the error is also logged, before the error page is rendered. This means that we end up calling ssrFixStacktrace twice — once when it's logged, and again when it's rendered. But since ssrFixStacktrace isn't idempotent, the second call should really be called ssrBreakStacktrace.

Suggested solution

We can work around it, allowing us to fix stack traces at render time regardless of whether they were already fixed for logging...

function fix_stack_trace(error) {
  const original = error.stack;
  vite.ssrFixStacktrace(error);
  const fixed = error.stack;
  error.stack = original;

  return fixed;
}

...but it would be neater if instead Vite exposed the internal ssrRewriteStacktrace helper, so that we weren't mutating error objects in the first place.

Alternative

No response

Additional context

No response

Validations

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