Change check for functional components for use with templates (#390)

Author: blake-newman

lib/loader.js

@@ -310,13 +310,13 @@ module.exports = function (content) {
         '  }\n' +
         '})()}\n'
     }
-    // check functional
+    // check functional components used with templates
     if (!isProduction) {
       output +=
-        'if (__vue_options__.functional) {console.error("' +
-          '[vue-loader] ' + fileName + ': functional components are not ' +
-          'supported and should be defined in plain js files using render ' +
-          'functions.' +
+        'if (__vue_options__.functional && typeof __vue_template__ !== "undefined") {' +
+          'console.error("' +
+          `[vue-loader] ${fileName}: functional components are not ` +
+          'supported with templates, they should use render functions.' +
         '")}\n'
     }
     // final export