Vite External Dep Error

when using import maps, vite command throws an error like below even if external module added to both rollupOption.external and optimizeDeps.exclude.

[vite] Internal server error: Failed to resolve import "external" from "index.js". Does the file exist?
  Plugin: vite:import-analysis
  File: /Users/.../index.js
  1  |  import external from 'external';
     |                        ^
  2  |  
  3  |  external.func();

vite build command succesfully builds the index.js and I think vite command should work same as vite build if the external module is excluded.