fix crash

Author: yulingtianxia

lib/main.js

@@ -181,7 +181,9 @@ function generateDartWithWorker(content, path, script) {
 
         let dartFilePath = writeOutputToFileByPath(result.dartCode, path)
         // collect all enumeratorTypeNames
-        result.enumeratorTypeNames.forEach(item => enumeratorTypeNames.push(item))
+        if (result.enumeratorTypeNames) {
+            result.enumeratorTypeNames.forEach(item => enumeratorTypeNames.push(item))
+        }
         // collect all packages
         if (projectName) {
             result.packages.forEach(item => packageSet.add(item))

test/test.js

@@ -1,4 +1,4 @@
-import { readFileSync } from "fs"
+import { readFileSync } from 'fs'
 import { program } from 'commander'
 
 function compareDartFiles(f1, f2) {