Make auto-fixing of stack traces optional when using ssrLoadModule

[Rich-Harris]

Clear and concise description of the problem

When an error occurs during SSR, the stack trace needs fixing in order to be correct:

try {
  result = mod.foo();
} catch (error) {
  vite.ssrFixStacktrace(error);
  handle_error(error);
}

But if the error occurred during ssrLoadModule, Vite will fix the stack trace before the error is thrown. As discussed in #7045, this results in a broken sourcemap at best and a cryptic "TypeError: Line must be greater than or equal to 1, got -1" error at worst:

try {
+ const mod = await vite.ssrLoadModule('my-module.js');
  result = mod.foo();
} catch (error) {
+ // yikes, we don't know if the stack trace was already fixed or not
- vite.ssrFixStacktrace(error);
  handle_error(error);
}

It's possible to work around it...

let mod;

try {
  mod = await vite.ssrLoadModule('my-module.js');
} catch (error) {
  handle_error(error);
}

try {
  result = mod.foo();
} catch (error) {
  vite.ssrFixStacktrace(error);
  handle_error(error);
}

...but when module loads are happening several function call boundaries away from the try/catch, this becomes problematic — all you can do is remove ssrFixStacktrace from the top-level catch and wrap everything except calls to ssrLoadModule with more granular try/catch blocks and do ssrFixStacktrace in those instead. It can get out of hand quite rapidly.

Suggested solution

For me, the ideal would be if ssrLoadModule didn't fix stack traces at all (or log errors, for that matter) — there's nothing particularly special about errors that occur during module load rather than inside a function.

Since that would be a breaking change, it could be an config option instead:

// vite.config.js, or inline config
const config = {
  ssr: {
    preserveStacktrace: true
  }
};

Alternative

Instead of putting the option in the config, it could be an option to ssrLoadModule itself. The docs suggest that ssrLoadModule already takes an options object...

...though I think that's incorrect?

vite/packages/vite/src/node/server/index.ts

Lines 364 to 372 in 489a7f1

	ssrLoadModule(url) {
	server._ssrExternals ||= resolveSSRExternal(
	config,
	server._optimizeDepsMetadata
	? Object.keys(server._optimizeDepsMetadata.optimized)
	: []
	)
	return ssrLoadModule(url, server)
	},

Regardless, an option like preserveStacktrace: true could be a solution here.

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[Rich-Harris]

How so? They don't appear at all related to me

[benmccann]

Here's the code that does it (it doesn't call ssrFixStacktrace, but invokes the same two methods):

vite/packages/vite/src/node/ssr/ssrModuleLoader.ts

Line 192 in 2debb9f

const stacktrace = ssrRewriteStacktrace(e.stack, moduleGraph)

[Niputi]

sorry. after reading it a second time now I see it's not related.
first time I read this, it somehow felt similar in my head

[benmccann]

I sent a PR for this: #7048