pass context even if there is no debug info

the context can then display an error
instead of crashing with a nullptr exception

src/twbl/types.h

@@ -196,7 +196,7 @@ class CServerBotStateOut
 			pCallback(aBuf, i + 1, pContext);
 		}
 #else
-		pCallback("to use tracing compile with -DTWBL_DEBUG=ON", 0, nullptr);
+		pCallback("to use tracing compile with -DTWBL_DEBUG=ON", 0, pContext);
 #endif
 	}