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UNUSED_EXTERNAL_IMPORT build warning with Vite, Rollup, or Nuxt

When bundling an application that uses @supabase/supabase-js, you may see warnings like:

"PostgrestError" is imported from external module "@supabase/postgrest-js" but never used in "...supabase-js/dist/index.mjs".
"FunctionRegion", "FunctionsError", "FunctionsFetchError", "FunctionsHttpError" and "FunctionsRelayError" are imported from external module "@supabase/functions-js" but never used in "...".

This is a false positive — your bundle is correct and no code is missing.

Why this happens#

@supabase/supabase-js re-exports error types like PostgrestError and FunctionsError so you can import them directly from @supabase/supabase-js. The build tool merges all imports from the same package into a single statement in the output:

// dist/index.mjs (simplified)
import { PostgrestClient, PostgrestError } from '@supabase/postgrest-js'
//       ^ used internally    ^ re-exported for you

Vite/Rollup checks which names from that import are referenced in the code body and flags PostgrestError as unused, because it only appears in an export statement — not called or assigned. The export itself is the real usage, but this check doesn't account for re-exports. Tree-shaking and bundle size are unaffected.

Suppress the warning#

Vite / Rollup (vite.config.js or rollup.config.js)#

export default {
  build: {
    rollupOptions: {
      onwarn(warning, warn) {
        if (warning.code === 'UNUSED_EXTERNAL_IMPORT' && warning.exporter?.includes('@supabase/'))
          return
        warn(warning)
      },
    },
  },
}

Nuxt (nuxt.config.ts)#

export default defineNuxtConfig({
  vite: {
    build: {
      rollupOptions: {
        onwarn(warning, warn) {
          if (warning.code === 'UNUSED_EXTERNAL_IMPORT' && warning.exporter?.includes('@supabase/'))
            return
          warn(warning)
        },
      },
    },
  },
})