Optionally make CSS reference/asset resolution failures errors instead of warnings?

[Mr0grog]

I have a build in which I’d like to ensure all the asset references in my CSS successfully resolve. At the moment, I get a warning like:

../../static/img/strikethrough.svg referenced in ../../static/img/strikethrough.svg didn't resolve at build time, it will remain unchanged to be resolved at runtime

…which is great, but the exit code is 0, and this is just a warning. Is there any way to make Vite treat this as an error instead? I’ve looked through the documentation and, if there’s an option, I’m certainly missing it!

(Obviously I can work around it my capturing stderr and grepping for the problems I’m concerned about… or maybe failing if there’s anything on on stderr, but it would be nice if I didn’t have to do that. As-is, I need to at least be careful about debug output on stderr. Not sure if there can be other non-warning/error output on stderr.)

[agammann]

You can promote this specific warning through Vite's customLogger. The unresolved CSS URL message goes through warnOnce in current Vite:

import { createLogger, defineConfig } from 'vite';

const logger = createLogger();
const originalWarnOnce = logger.warnOnce;
logger.warnOnce = (message, options) => {
  if (message.includes("didn't resolve at build time")) {
    throw new Error(message);
  }
  originalWarnOnce(message, options);
};

export default defineConfig({ customLogger: logger });

I tested this on Vite 8.3.3: a missing CSS url() made vite build exit 1, while adding the asset made the build succeed. This avoids scraping stderr and leaves other warnings alone. See customLogger.

[Icaro0310]

There's no built-in option for that, Vite treats unresolved url() references as warnings by design. The way I force a failure is a custom logger that re-throws on that specific message:

// vite.config.ts
import { createLogger, defineConfig } from 'vite'

const logger = createLogger()
const warn = logger.warn
logger.warn = (msg, options) => {
 if (msg.includes("didn't resolve at build time")) throw new Error(msg)
 warn(msg, options)
}

export default defineConfig({ customLogger: logger })

Throwing propagates through the build so the process exits non-zero and CI catches it. If you'd rather collect every unresolved reference first and fail at the end, push them to an array in the warn hook and throw in a closeBundle plugin hook instead.

—
Related work of mine: github.com/Icaro0310 · Website: icaro0310.github.io