check if steam not found

Which also fixes the crash if steam was on login window

src/client/component/steam_proxy.cpp

@@ -36,6 +36,11 @@ namespace steam_proxy
 				return;
 			}
 			
+			if (!FindWindowA(0, "Steam"))
+			{
+				return;
+			}
+
 			this->load_client();
 			this->clean_up_on_error();