[adapter-vercel] Page visits return `500: INTERNAL_SERVER_ERROR` possibly due to missing modules that are marked as `external` for `esbuild`

Describe the bug

When using a module that doesn’t play well with esbuild, (eg: html-minifier), deploying to Vercel is technically successful but results in failing page visits.

In my case, I’ve used the html-minifier package to write a simple handle hook that minifies html.

The deploys were previously showing warnings that certain relative paths needed to be marked as external for esbuild. All of these warnings had ties to uglify-js, a dependency of html-minifier. These warnings disappeared when html-minifier was marked as external

Reproduction

Here is a link to a reproduction.

Here are the steps I took to create the reproduction:

• Start with default skeleton with all extras enabled.
• Install html-minifier and create a simple handle hook that minifies html. At this point, I got the following warnings on Vercel:

Warnings on Vercel deployment log

▲ [WARNING] "../lib/utils.js" should be marked as external for use with "require.resolve"

    node_modules/.pnpm/uglify-js@3.15.2/node_modules/uglify-js/tools/node.js:4:20:
      4 │     require.resolve("../lib/utils.js"),
        ╵                     ~~~~~~~~~~~~~~~~~

▲ [WARNING] "../lib/ast.js" should be marked as external for use with "require.resolve"

    node_modules/.pnpm/uglify-js@3.15.2/node_modules/uglify-js/tools/node.js:5:20:
      5 │     require.resolve("../lib/ast.js"),
        ╵                     ~~~~~~~~~~~~~~~

▲ [WARNING] "../lib/transform.js" should be marked as external for use with "require.resolve"

    node_modules/.pnpm/uglify-js@3.15.2/node_modules/uglify-js/tools/node.js:6:20:
      6 │     require.resolve("../lib/transform.js"),
        ╵                     ~~~~~~~~~~~~~~~~~~~~~

▲ [WARNING] "../lib/parse.js" should be marked as external for use with "require.resolve"

    node_modules/.pnpm/uglify-js@3.15.2/node_modules/uglify-js/tools/node.js:7:20:
      7 │     require.resolve("../lib/parse.js"),
        ╵                     ~~~~~~~~~~~~~~~~~

▲ [WARNING] "../lib/scope.js" should be marked as external for use with "require.resolve"

    node_modules/.pnpm/uglify-js@3.15.2/node_modules/uglify-js/tools/node.js:8:20:
      8 │     require.resolve("../lib/scope.js"),
        ╵                     ~~~~~~~~~~~~~~~~~

▲ [WARNING] "../lib/compress.js" should be marked as external for use with "require.resolve"

    node_modules/.pnpm/uglify-js@3.15.2/node_modules/uglify-js/tools/node.js:9:20:
      9 │     require.resolve("../lib/compress.js"),
        ╵                     ~~~~~~~~~~~~~~~~~~~~

▲ [WARNING] "../lib/output.js" should be marked as external for use with "require.resolve"

    node_modules/.pnpm/uglify-js@3.15.2/node_modules/uglify-js/tools/node.js:10:20:
      10 │     require.resolve("../lib/output.js"),
         ╵                     ~~~~~~~~~~~~~~~~~~

▲ [WARNING] "../lib/sourcemap.js" should be marked as external for use with "require.resolve"

    node_modules/.pnpm/uglify-js@3.15.2/node_modules/uglify-js/tools/node.js:11:20:
      11 │     require.resolve("../lib/sourcemap.js"),
         ╵                     ~~~~~~~~~~~~~~~~~~~~~

▲ [WARNING] "../lib/mozilla-ast.js" should be marked as external for use with "require.resolve"

    node_modules/.pnpm/uglify-js@3.15.2/node_modules/uglify-js/tools/node.js:12:20:
      12 │     require.resolve("../lib/mozilla-ast.js"),
         ╵                     ~~~~~~~~~~~~~~~~~~~~~~~

▲ [WARNING] "../lib/propmangle.js" should be marked as external for use with "require.resolve"

    node_modules/.pnpm/uglify-js@3.15.2/node_modules/uglify-js/tools/node.js:13:20:
      13 │     require.resolve("../lib/propmangle.js"),
         ╵                     ~~~~~~~~~~~~~~~~~~~~~~

▲ [WARNING] "../lib/minify.js" should be marked as external for use with "require.resolve"

    node_modules/.pnpm/uglify-js@3.15.2/node_modules/uglify-js/tools/node.js:14:20:
      14 │     require.resolve("../lib/minify.js"),
         ╵                     ~~~~~~~~~~~~~~~~~~

▲ [WARNING] "./exports.js" should be marked as external for use with "require.resolve"

    node_modules/.pnpm/uglify-js@3.15.2/node_modules/uglify-js/tools/node.js:15:20:
      15 │     require.resolve("./exports.js"),
         ╵                     ~~~~~~~~~~~~~~

• Install the adapter-vercel and specify html-minifier as an external module.

Logs

Here’s an example log for functions that are invoked when a user visits the deployed site:

ERROR	Cannot find module 'html-minifier'
      Did you forget to add it to "dependencies" in `package.json`?
      Runtime exited with error: exit status 1

System Info

System:
    OS: Linux 5.10 Manjaro Linux
    CPU: (8) x64 Intel(R) Core(TM) i7-4700HQ CPU @ 2.40GHz
    Memory: 2.90 GB / 15.52 GB
    Container: Yes
    Shell: 5.8 - /usr/bin/zsh
  Binaries:
    Node: 14.18.1 - ~/.nvm/versions/node/v14.18.1/bin/node
    Yarn: 1.22.10 - ~/.nvm/versions/node/v14.18.1/bin/yarn
    npm: 6.14.15 - ~/.nvm/versions/node/v14.18.1/bin/npm
  Browsers:
    Brave Browser: 96.1.32.115
    Firefox: 95.0
  npmPackages:
    @sveltejs/adapter-vercel: next => 1.0.0-next.46 
    @sveltejs/kit: next => 1.0.0-next.294 
    svelte: ^3.46.4 => 3.46.4

Severity

blocking an upgrade

Additional Information

• I’m using pnpm as my package manager
• Some relevant issues and PRs: #2931, #3614, #3588, #869, #3306

I think I might be missing some configuration.

Any help is appreciated! Thank you for your time!

[Rich-Harris]

Going to assume this was fixed by #4969 and close it — feel free to open a new issue if it’s still happening with current versions of everything

[Rich-Harris]

This will hopefully be fixed by #4969