Fix for NPE on empty MMS PDU

src/org/thoughtcrime/securesms/service/MmsDownloader.java

@@ -71,13 +71,13 @@ public class MmsDownloader extends MmscProcessor {
                                                              getApnInformation());
       RetrieveConf retrieved = (RetrieveConf)new PduParser(pdu).parse();
 
-      for (int i=0;i<retrieved.getBody().getPartsNum();i++) {
-	Log.w("MmsDownloader", "Sent MMS part of content-type: " + new String(retrieved.getBody().getPart(i).getContentType()));
-      }
-
       if (retrieved == null)
         throw new IOException("Bad retrieved PDU");
 
+      for (int i=0;i<retrieved.getBody().getPartsNum();i++) {
+        Log.w("MmsDownloader", "Sent MMS part of content-type: " +
+              new String(retrieved.getBody().getPart(i).getContentType()));
+      }
 
       if (retrieved.getSubject() != null && WirePrefix.isEncryptedMmsSubject(retrieved.getSubject().getString())) {
         long messageId = mmsDatabase.insertSecureMessageReceived(retrieved, item.getContentLocation(), item.getThreadId());
@@ -177,6 +177,4 @@ public class MmsDownloader extends MmscProcessor {
   protected String getConnectivityAction() {
     return SendReceiveService.DOWNLOAD_MMS_CONNECTIVITY_ACTION;
   }
-
-
 }