Cannot import a module for side effects only

[jakemckown]

My project uses brace, an NPM variant of the Ace code editor. To support languages and themes, imports with side effects only are required:

import * as ace from 'brace'; // Adds ace property to global, but also has exports
import 'brace/mode/python';   // Adds support for Python language to global.ace, but has no exports
import 'brace/theme/github';  // Adds support for GitHub theme to global.ace, but has no exports

Attempting to snowpack build --verbose fails:

[snowpack] FAILURE: Error: 'default' is not exported by node_modules\brace\mode\python.js, imported by snowpack-wrap:C:\...\node_modules\brace\mode\python.js
[snowpack] Failed to load snowpack-wrap:C:/.../node_modules/brace/mode/python.js
  'default' is not exported by node_modules\brace\mode\python.js, imported by snowpack-wrap:C:\...\node_modules\brace\mode\python.js
[snowpack] Install failed.
[snowpack] Error: Install failed.
    at Object.install (C:\...\node_modules\snowpack\lib\index.js:49254:19)
    at runMicrotasks (<anonymous>)
    at processTicksAndRejections (node:internal/process/task_queues:94:5)
    at async Object.run (C:\...\node_modules\snowpack\lib\index.js:49313:25)
    at async installOptimizedDependencies (C:\...\node_modules\snowpack\lib\index.js:111900:27)
    at async installDependencies (C:\...\node_modules\snowpack\lib\index.js:112169:31)
    at async build (C:\...\node_modules\snowpack\lib\index.js:112239:25)
    at async Object.command (C:\...\node_modules\snowpack\lib\index.js:112392:9)
    at async cli (C:\...\node_modules\snowpack\lib\index.js:133123:9)
error Command failed with exit code 1.

Both imports cause the error. If I remove the first import to 'brace/mode/python', it still fails on the second import:

[snowpack] FAILURE: Error: 'default' is not exported by node_modules\brace\theme\github.js, imported by snowpack-wrap:C:\...\node_modules\brace\theme\github.js
[snowpack] Failed to load snowpack-wrap:C:/.../node_modules/brace/theme/github.js
  'default' is not exported by node_modules\brace\theme\github.js, imported by snowpack-wrap:C:\...\node_modules\brace\theme\github.js
...
error Command failed with exit code 1.

Is there some Snowpack config option to allow modules to run their side effects and then ignore them for the build pipeline? I've seen other projects that use side-effect-only imports and have to imagine they would have similar issues if using Snowpack. For example, TensorFlow.js:

@tensorflow/tfjs/src/index.ts

import '@tensorflow/tfjs-core';
import '@tensorflow/tfjs-core/dist/register_all_gradients';
import '@tensorflow/tfjs-core/dist/public/chained_ops/register_all_chained_ops';

// Import and register backends.
import '@tensorflow/tfjs-backend-cpu';
import '@tensorflow/tfjs-backend-webgl';

@tensorflow/tfjs-core/src/index.ts

// Required side effectful code.
import './base_side_effects';

For reference, here's my current config:

snowpack.config.js

module.exports = {
  mount: {
    public: {
      url: '/',
      static: true
    },
    src: {
      url: '/dist'
    },
  },
  plugins: [
    ['@snowpack/plugin-svelte', {
      hmrOptions: {
        noPreserveState: true
      }
    }],
    '@snowpack/plugin-typescript',
    '@snowpack/plugin-postcss',
    ['snowpack-plugin-terser', {
      terserOptions: {
        compress: {
          arguments: true,
          passes: 2
        }
      }
    }]
  ],
  devOptions: {
    port: 5000
  },
  buildOptions: {
    clean: true
  },
  optimize: {
    bundle: true,
    minify: true
  }
};

svelte.config.js

module.exports = {
  preprocess: require('svelte-preprocess')({
    defaults: {
      script: 'typescript'
    }
  })
};

[melissamcewen]

Hi @jakemckown do you have a working repo where I could run your code? That would help me replicate this. I feel like this should work but I'll ask the rest of the maintainers about it.

[jakemckown]

Hi @melissamcewen, I set up a stripped-down repo at https://github.com/jakemckown/snowpack-import that gives me the same error. In src/App.svelte, you'll see the code

import * as ace from 'brace';

// Languages
import 'brace/mode/c_cpp';
import 'brace/mode/javascript';
import 'brace/mode/python';
import 'brace/mode/rust';

// Themes
import 'brace/theme/chrome';
import 'brace/theme/github';
import 'brace/theme/monokai';
import 'brace/theme/xcode';

I included multiple languages and themes to show that if you delete any one of them and try to snowpack dev or snowpack build, it will still cause the error.

I appreciate your time on this.

[Akari0731]

Getting Error for brace too. Message is:
Module "brace/theme/solarized_dark" has no exported member "default". Did you mean to use "import default from 'brace/theme/solarized_dark'" instead

I'm using

"snowpack": "3.8.0"
"brace": "^0.11.1"

I understand that brace is not maintained well, but it'd be really appreciated if snowpack can support this case and it might help/solve other case too!!