build - fix error swallowing on dev

gulpfile.js

@@ -306,6 +306,17 @@ function bundleTask(opts) {
     return (
 
       bundler.bundle()
+
+      // handle errors
+      .on('error', (err) => {
+        beep()
+        if (opts.watch) {
+          console.warn(err.stack)
+        } else {
+          throw err
+        }
+      })
+      
       // convert bundle stream to gulp vinyl stream
       .pipe(source(opts.filename))
       // inject variables into bundle
@@ -328,3 +339,7 @@ function bundleTask(opts) {
     )
   }
 }
+
+function beep () {
+  process.stdout.write('\x07')
+}