nodejs / nodejs/node

Missing import trace from error stack when loading a module throws an error

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esm feature request
Langage dominant
JavaScript
Étoiles
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Forks
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Merge moyen
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PR mergées (30 j)
283

Description

Version

v16.16.0

Platform

Linux 5.4.0-139-generic #156-Ubuntu SM x86_64 GNU/Linux

Subsystem

modules

What steps will reproduce the bug?

Consider:

// foo.mjs
import './bar.mjs';
// bar.mjs
throw new Error('bar failed');

Run node foo.mjs.

How often does it reproduce? Is there a required condition?

Always.

What is the expected behavior?

The stack trace from the error should include a reference to foo.mjs line 1 showing where bar was imported from.

What do you see instead?
file:///.../bar.mjs:1
throw new Error('bar failed');
      ^

Error: bar failed
    at file:///.../bar.mjs:1:7
    at ModuleJob.run (node:internal/modules/esm/module_job:198:25)
    at async Promise.all (index 0)
    at async ESMLoader.import (node:internal/modules/esm/loader:385:24)
    at async loadESM (node:internal/process/esm_loader:88:5)
    at async handleMainPromise (node:internal/modules/run_main:61:12)

Note that the stack trace does not mention foo anywhere. This is not helpful, especially if the error is specifically about how and when bar is imported. For example, it might be a singleton and you're mistakenly creating a duplicate by loading it from both import and require, or it might need something else to be set up on the global first and you're loading it in the wrong order.

The above stack is from node 16. Node 18 produces a shorter but similarly lacking stack:

file:///.../bar.mjs:1
throw new Error('bar failed');
      ^

Error: bar failed
    at file:///.../bar.mjs:1:7
    at ModuleJob.run (node:internal/modules/esm/module_job:194:25)
Additional information

I am aware that import() and top-level await complicates this, since modules may be effectively loading in parallel (asynchronously behind the scenes). However, it is absolutely essential that this information is made available somehow.

If the output ends up being a list of all modules trying to load the offending module then great, as long as this list is in the order the imports were encountered then that should allow debugging this kind of thing.

At the moment when this occurs it's simply impossible to debug. Since import gets hoisted by the language you can't even add console.log statements around the place to trace what's happening like you can with require. Literally the only option to debug this is to comment out all the imports and re-enable one-by-one (recursively) until you locate the problem. And in practice this inevitably breaks something else, so it's completely unworkable.

Guide de contribution

Ouvrir le guide de contribution

Par où commencer

  1. Lisez l'issue en entier, puis le guide de contribution du projet.
  2. Signalez en commentaire que vous la prenez — cela évite que deux personnes fassent le même travail.
  3. Forkez le dépôt et travaillez sur une branche.
  4. Ouvrez une pull request qui référence le numéro de l'issue.

Piste de recherche

Commencez par reproduire le problème avec les modules foo.mjs et bar.mjs en utilisant node foo.mjs, puis examinez le sous-système de modules impliqué dans le chargement de ESM. Suivez la propagation des erreurs à travers le chemin d’importation et de chargement des modules. Le travail est terminé lorsque les informations de pile résultantes identifient la ligne 1 de foo.mjs, tout en prenant en compte les cas d’importation asynchrone décrits.

Rédigé par le modèle d'indexation à partir du texte de l'issue.

Évaluation

Stack technique
javascript
Domaine
backend
Type d'issue
Bug
Difficulté
4/5
Temps estimé
3-5 jours
Activité
Calme
Clarté
Plutôt claire
Accessibilité débutants
45/100

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