TypeError: Cannot read properties of undefined (reading 'indexOf')

[janosh]

Rollup Version

3.27.1

Operating System (or Browser)

macOS

Node Version (if applicable)

No response

Link To Reproduction

https://stackblitz.com/edit/rollup-repro-ughg9c?file=package.json

Expected Behaviour

npm run build succeeds.

Actual Behaviour

Lazy computing decoded mappings in #5075 seems to cause undefined mappings at vite build time in SvelteKit.

https://github.com/janosh/elementari/actions/runs/5754572660/job/15600143441#step:6:18

vite v4.4.8 building SSR bundle for production...
transforming...
✓ 5 modules transformed.
✓ built in 556ms
Cannot read properties of undefined (reading 'indexOf')
error during build:
TypeError: Cannot read properties of undefined (reading 'indexOf')
    at indexOf (file:///home/runner/work/elementari/elementari/node_modules/rollup/dist/es/shared/node-entry.js:91:26)
    at decode (file:///home/runner/work/elementari/elementari/node_modules/rollup/dist/es/shared/node-entry.js:54:22)
    at get mappings [as mappings] (file:///home/runner/work/elementari/elementari/node_modules/rollup/dist/es/shared/node-entry.js:13281:37)
    at decodedSourcemap (file:///home/runner/work/elementari/elementari/node_modules/rollup/dist/es/shared/node-entry.js:13254:13)
    at file:///home/runner/work/elementari/elementari/node_modules/rollup/dist/es/shared/node-entry.js:13997:104
    at Array.map (<anonymous>)
    at Module.setSource (file:///home/runner/work/elementari/elementari/node_modules/rollup/dist/es/shared/node-entry.js:13997:46)
    at ModuleLoader.addModuleSource (file:///home/runner/work/elementari/elementari/node_modules/rollup/dist/es/shared/node-entry.js:24523:[20](https://github.com/janosh/elementari/actions/runs/5754572660/job/15600143441#step:6:21))

[lukastaegert]

Unfortunately your npm run build does not run for me in your reproduction. There are several images missing, and when I remove the references I get other errors. Could have a look? In any case, that sounds rather serious, so I will try to re-release the previous version for now.
cc @thebanjomatic, maybe you have an idea how to handle this?

[thebanjomatic]

I'll take a look at this today.

[thebanjomatic]

This is failing because of unexpected input. One of the plugins is returning {mappings: null} and the types are expecting {mappings: ''} to signal the empty sourcemap. I have a PR that should be ready soon that loosens the types for the decodedSourcemap function to cover mappings; null | undefined, and a few other small changes to ensure that we are then handling those cases correctly.

[thebanjomatic]

@lukastaegert A fix for the above issue is in the second commit of the linked PR: #5087

[thebanjomatic]

FYI I also had issues with the stackblitz reproducer, but I was able to reproduce by pulling down https://github.com/janosh/elementari and setting a resolution to rollup 3.27.1. Then I tested the fix there by linking in my built branch.

It looks like this particular problem is stemming from this plugin returning mappings: null:
https://github.com/mattjennings/mdsvexamples/blob/eae8ffbf808f59aeec91a00a4df278eb410f6d6f/src/lib/plugin.js#L134C13-L136

[rollup-bot]

This issue has been resolved via #5087 as part of rollup@3.28.0. You can test it via npm install rollup.