Missing content directory throws unhelpful error

[TheOtterlord]

What version of starlight are you using?

0.10.1

What version of astro are you using?

3.1.2

What package manager are you using?

npm

What operating system are you using?

Linux

What browser are you using?

Firefox

Describe the Bug

A missing content folder throws an obscure error. It's not an error I'd expect people to frequently encounter, but I this we can add a more useful error, just to cover this case.

11:48:31 [vite] Error when evaluating SSR module /node_modules/@astrojs/starlight/utils/routing.ts:
|- TypeError: (intermediate value).map is not a function
    at eval (/home/otterlord/Documents/Repos/api/test/node_modules/@astrojs/starlight/utils/routing.ts:10:66)
    at async instantiateModule (file:///home/otterlord/Documents/Repos/api/test/node_modules/vite/dist/node/chunks/dep-df561101.js:55974:9)

11:48:31 [vite] Error when evaluating SSR module /home/otterlord/Documents/Repos/api/test/node_modules/@astrojs/starlight/index.astro: failed to import "/node_modules/@astrojs/starlight/utils/routing.ts"
|- TypeError: (intermediate value).map is not a function
    at eval (/home/otterlord/Documents/Repos/api/test/node_modules/@astrojs/starlight/utils/routing.ts:10:66)
    at async instantiateModule (file:///home/otterlord/Documents/Repos/api/test/node_modules/vite/dist/node/chunks/dep-df561101.js:55974:9)

 error   (intermediate value).map is not a function
  File:
    /home/otterlord/Documents/Repos/api/test/node_modules/@astrojs/starlight/utils/routing.ts:38:66
  Code:
    37 | /** All entries in the docs content collection. */
    > 38 | const docs: StarlightDocsEntry[] = (await getCollection('docs')).map(({ slug, ...entry }) => ({
         |                                                                  ^
      39 |   ...entry,
      40 |   slug: normalizeIndexSlug(slug),
      41 | }));
  Stacktrace:
TypeError: (intermediate value).map is not a function
    at /home/otterlord/Documents/Repos/api/test/node_modules/@astrojs/starlight/utils/routing.ts:38:66
    at async instantiateModule (file:///home/otterlord/Documents/Repos/api/test/node_modules/vite/dist/node/chunks/dep-df561101.js:55974:9)

My proposal would be to check getCollection returns an array, then if not, throw an error about content not being found.

Link to Minimal Reproducible Example

No response

Participation

• I am willing to submit a pull request for this issue.

[TheOtterlord]

Adding a note, but not closing yet until I confirm the cause. It looks like this is related to a behaviour change in Astro, post 3.0.6. I need to confirm if this is intentional. Tf it is, I'll continue working on my edge-case fix, if not, I'll close this and follow up with core

[TheOtterlord]

Confirming this was an accepted behaviour change in 3.1.2 (withastro/astro#8336). I'll add something to address this in Starlight.

[TheOtterlord]

Another note. The behaviour introduced in 3.1.2 is not what is expected, so we'll have to wait for a patch release to finalise behaviour before I can fix this.