Eleventy templates esm related errors are rather unhelpful

[thoughtsunificator]

Operating system

Linux

Eleventy

3.0.0

Node

Node.js v24.0.0-pre

Describe the bug

A template file, foo.11ty.js with the following code:

export const

yields:

[11ty] Problem writing Eleventy templates:
[11ty] Unexpected end of input (via SyntaxError)
[11ty] 
[11ty] Original error stack trace: SyntaxError: Unexpected end of input
[11ty]     at compileSourceTextModule (node:internal/modules/esm/utils:338:16)
[11ty]     at ModuleLoader.moduleStrategy (node:internal/modules/esm/translators:103:18)
[11ty]     at #translate (node:internal/modules/esm/loader:437:12)
[11ty]     at ModuleLoader.loadAndTranslate (node:internal/modules/esm/loader:484:27)
[11ty]     at async ModuleJob._link (node:internal/modules/esm/module_job:115:19)
[11ty] Wrote 0 files in 0.03 seconds (v3.0.0)

The problem is that there are no clear indicators as to the origins of the error.

Reproduction steps

Assuming linux and bash:

[foo@bar ~]$ echo "export const" > /tmp/foo.11ty.js && npx @11ty/eleventy@3.0.0 --input=/tmp/foo.11ty.js

Expected behavior

I should be getting a real indicator as to the origins of the error.

Reproduction URL

No response

Screenshots

No response

[thoughtsunificator]

This is what you'd be getting running the file directly:

[foo@bar ~]$ node /tmp/foo.11ty.js 
file:///tmp/foo.11ty.js:2

SyntaxError: Unexpected end of input
    at compileSourceTextModule (node:internal/modules/esm/utils:338:16)
    at ModuleLoader.moduleStrategy (node:internal/modules/esm/translators:103:18)
    at #translate (node:internal/modules/esm/loader:437:12)
    at ModuleLoader.loadAndTranslate (node:internal/modules/esm/loader:484:27)
    at async ModuleJob._link (node:internal/modules/esm/module_job:115:19)

Node.js v24.0.0-pre

[thoughtsunificator]

The same problem also occurs with:

[foo@bar ~]$ echo "foo" > /tmp/foo.11ty.js && npx @11ty/eleventy@3.0.0 --input=/tmp/foo.11ty.js

[thoughtsunificator]

Even worse if your eleventy config contains invalid syntax such as:

import foo from "./bar" with { type: "json" }

[11ty] 1. A problem was encountered looking for JavaScript dependencies in ESM file: ./eleventy.config.js. This only affects --watch and --serve behavior and does not affect your build. (via EleventyBaseError)
[11ty] 2. Unexpected token (2:7) (via SyntaxError)

[Ryuno-Ki]

Reminds me on #3491.
That is, perhaps the issue is with Acorn that Eleventy is using under the hood.

REPL shows the same behavior

(Acorn doesn't understand with yet)

[zachleat]

Related #3580

[zachleat]

Error messaging will show file path in v3.0.1-alpha.1—thank you!

[11ty] Problem writing Eleventy templates:
[11ty] 1. There was a problem importing 'foo.11ty.js' via import(esm) (via EleventyImportError)
[11ty] 2. Unexpected end of input (via SyntaxError)
[11ty] 
[11ty] Original error stack trace: SyntaxError: Unexpected end of input
[11ty]     at compileSourceTextModule (node:internal/modules/esm/utils:338:16)
[11ty]     at ModuleLoader.moduleStrategy (node:internal/modules/esm/translators:102:18)
[11ty]     at #translate (node:internal/modules/esm/loader:437:12)
[11ty]     at ModuleLoader.loadAndTranslate (node:internal/modules/esm/loader:484:27)
[11ty]     at async ModuleJob._link (node:internal/modules/esm/module_job:115:19)
[11ty] Wrote 0 files in 0.02 seconds (v3.0.1-alpha.1)