Always make sure we don't dereference possibly invalid

From: Erik Hovland <erik@hovland.org>

pointers w/out checking first.
---

 programs/mythbackend/mainserver.cpp |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/programs/mythbackend/mainserver.cpp b/programs/mythbackend/mainserver.cpp
index 3ed32f7..5a82686 100644
--- a/programs/mythbackend/mainserver.cpp
+++ b/programs/mythbackend/mainserver.cpp
@@ -1050,7 +1050,7 @@ void MainServer::HandleDone(MythSocket *socket)
 
 void MainServer::SendResponse(MythSocket *socket, QStringList &commands)
 {
-    if (getPlaybackBySock(socket) || getFileTransferBySock(socket))
+    if (socket && (getPlaybackBySock(socket) || getFileTransferBySock(socket)))
     {
         socket->writeStringList(commands);
     }