Check for null account for monkey.

Fixes b/6335995 top java crash in JRN12B: Gmail: NullPointerException at com.android.mail.compose.ComposeActivity.setAccount

Change-Id: Id11a1163eb7375324bc04bee3d6524b8be63b9d1
diff --git a/src/com/android/mail/compose/ComposeActivity.java b/src/com/android/mail/compose/ComposeActivity.java
index c87260e..9a4ccb1 100644
--- a/src/com/android/mail/compose/ComposeActivity.java
+++ b/src/com/android/mail/compose/ComposeActivity.java
@@ -407,7 +407,9 @@
 
     @VisibleForTesting
     void setAccount(Account account) {
-        assert(account != null);
+        if (account == null) {
+            return;
+        }
         if (!account.equals(mAccount)) {
             mAccount = account;
             mCachedSettings = mAccount.settings;