Revert "fix: build cannot exit (close: #580)"

This reverts commit fa473a72.

lib/build.js

@@ -93,9 +93,6 @@ module.exports = async function build (sourceDir, cliOptions = {}) {
   const relativeDir = path.relative(process.cwd(), outDir)
   logger.success(`\n${chalk.green('Success!')} Generated static files in ${chalk.cyan(relativeDir)}.\n`)
 
-  // fix: #580 build cannot exit.
-  process.exit(0)
-
   // --- helpers ---
 
   function compile (config) {