fix: improve error message when entry is missing w/ --target lib

close #1051

packages/@vue/cli-service/lib/commands/build/resolveLibConfig.js

@@ -1,15 +1,31 @@
+const fs = require('fs')
 const path = require('path')
 
 module.exports = (api, { entry, name }, options) => {
+ // setting this disables app-only configs
+ process.env.VUE_CLI_TARGET = 'lib'
+ // inline all static asset files since there is no publicPath handling
+ process.env.VUE_CLI_INLINE_LIMIT = Infinity
+
+ const { log, error } = require('@vue/cli-shared-utils')
+ const abort = msg => {
+ log()
+ error(msg)
+ process.exit(1)
+ }
+
+ if (!fs.existsSync(api.resolve(entry))) {
+ abort(
+ `Failed to resolve lib entry: ${entry}${entry === `src/App.vue` ? ' (default)' : ''}. ` +
+ `Make sure to specify the correct entry file.`
+ )
+ }
+
  const libName = (
  name ||
  api.service.pkg.name ||
  path.basename(entry).replace(/\.(jsx?|vue)$/, '')
  )
- // setting this disables app-only configs
- process.env.VUE_CLI_TARGET = 'lib'
- // inline all static asset files since there is no publicPath handling
- process.env.VUE_CLI_INLINE_LIMIT = Infinity
 
  function genConfig (format, postfix = format, genHTML) {
  const config = api.resolveChainableWebpackConfig()