JIT mode fails when no input CSS is provided

[sumanthratna]

What version of Tailwind CSS are you using?

v2.1.0

What version of Node.js are you using?

v12.14.1

What browser are you using?

N/A

What operating system are you using?

macOS

Reproduction repository

https://github.com/sumanthratna/tailwind-2.1-noinput-repro

when I set mode: 'jit' and run yarn tailwindcss build, I get this error:

yarn run v1.22.10
$ /private/tmp/huh/node_modules/.bin/tailwindcss build

warn - You have enabled the JIT engine which is currently in preview.
warn - Preview features are not covered by semver, may introduce breaking changes, and can change at any time.
  
   🚫 TypeError [ERR_INVALID_ARG_TYPE]: The "url" argument must be of type string. Received type undefined
    at validateString (internal/validators.js:112:11)
    at Url.parse (url.js:155:3)
    at Object.urlParse [as parse] (url.js:150:13)
    at trackModified (/private/tmp/huh/node_modules/tailwindcss/jit/lib/setupContext.js:230:24)
    at /private/tmp/huh/node_modules/tailwindcss/jit/lib/setupContext.js:726:38
    at /private/tmp/huh/node_modules/tailwindcss/jit/index.js:35:47
    at LazyResult.runOnRoot (/private/tmp/huh/node_modules/postcss/lib/lazy-result.js:303:16)
    at LazyResult.runAsync (/private/tmp/huh/node_modules/postcss/lib/lazy-result.js:355:26)
    at LazyResult.async (/private/tmp/huh/node_modules/postcss/lib/lazy-result.js:205:30)
    at LazyResult.then (/private/tmp/huh/node_modules/postcss/lib/lazy-result.js:190:17)
  
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

What I'm expecting is the Tailwind build as if I provided the default Tailwind CSS file (this feature was introduced a while ago, so I think this is a regression)

I didn't see this error when using https://github.com/tailwindlabs/tailwindcss-jit

Also, the docs seem to suggest yarn postcss tailwindcss, but when I try that, I get this error (#3977):

Input Error: You must pass a valid list of files to parse

[sumanthratna]

will be closed by #3978

[RobinMalfait]

Hey! Thank you for your bug report!
Much appreciated! 🙏

Sorry about that! It should be fixed by #3978, can you try and updating to 2.1.1 and see if that works for you?

[sumanthratna]

@RobinMalfait v2.1.1 works great! thanks for the quick fix