Don't break if we terminate during a changes reader restart
diff --git a/src/cassim_metadata_cache.erl b/src/cassim_metadata_cache.erl
index 1eb0fc9..335256b 100644
--- a/src/cassim_metadata_cache.erl
+++ b/src/cassim_metadata_cache.erl
@@ -125,6 +125,8 @@
     {noreply, State}.
 
 
+terminate(_Reason, #st{changes_pid = undefined}) ->
+    ok;
 terminate(_Reason, #st{changes_pid = Pid}) ->
     exit(Pid, kill),
     ok.