fix: handle results for undefined part file.

Author: yulingtianxia

index.js

@@ -1,14 +1,12 @@
 import { main } from './lib/main.js'
 
-let ocPath = 'test/objc/NetworkRequest.h'
-let javaPath = 'test/java/helloworld.java'
+let path = 'test/objc/NetworkRequest.h'
+// let path = 'test/java/helloworld.java'
 let option = {
     output: 'test/dart',
     // template: 'plugin',
     // projectName: 'testPlugin'
 }
 
-// run objc
-main(ocPath, option, true)
-// run java
-main(javaPath, option, false)
+// run
+main(path, option, true)

lib/main.js

@@ -6,7 +6,7 @@ import { Worker } from 'worker_threads'
 import DNObjectiveCConverter from './objc/DNObjectiveCConverter.js'
 import DNJavaConverter from './java/DNJavaConverter.js'
 
-let dnPartExtension = 'dnpart'
+const dnPartExtension = 'dnpart'
 var outputDir
 var projectName
 var packageSet = new Set()
@@ -68,7 +68,7 @@ function writeOutputToFileByPath(result, srcPath) {
     var srcFile = srcPath.substr(srcPath.lastIndexOf('/') + 1)
     var components
     if (srcFile.endsWith(dnPartExtension)) {
-        partExtension = srcFile.split('.').slice(-2).join('.')
+        const partExtension = srcFile.split('.').slice(-2).join('.')
         components = srcFile.split('.').slice(0, -3)
         components.push('dart')
         components.push(partExtension)
@@ -201,7 +201,7 @@ async function runWorkItems(workItems) {
         })
         return Promise.all(ps).then((results) => {
             // merge files
-            mergeFiles(results)
+            mergeFiles(results.filter((f) => f != undefined))
         })
     })
     await Promise.all(promises)