[Android] fix memleak for apm
diff --git a/android/sdk/src/main/java/com/taobao/weex/performance/WXInstanceApm.java b/android/sdk/src/main/java/com/taobao/weex/performance/WXInstanceApm.java
index 12a09f1..4f99696 100644
--- a/android/sdk/src/main/java/com/taobao/weex/performance/WXInstanceApm.java
+++ b/android/sdk/src/main/java/com/taobao/weex/performance/WXInstanceApm.java
@@ -391,7 +391,7 @@
         exceptionRecord.clear();
         mUIHandler.removeCallbacks(jsPerformanceCallBack);
         onStage(KEY_PAGE_STAGES_DESTROY);
-        if (!mHasInit){
+        if (mHasInit && null != apmInstance){
             apmInstance.onEnd();
         }
         mEnd = true;