Fixing missing null check in trackTransaction

Author: arnaud-roland

android/src/main/java/tech/bam/RNBatchPush/RNBatchModule.java

@@ -575,7 +575,11 @@ public void userData_trackEvent(String name, String label, ReadableMap serialize
 
     @ReactMethod
     public void userData_trackTransaction(double amount, ReadableMap data) {
-        Batch.User.trackTransaction(amount, new JSONObject(data.toHashMap()));
+        JSONObject transactionData = null;
+        if (data != null) {
+            transactionData = new JSONObject(data.toHashMap());
+        }
+        Batch.User.trackTransaction(amount, transactionData);
     }
 
     @ReactMethod