Fallback to hardcoded icon on Linux if icon not found in theme

src/main.cpp

@@ -162,7 +162,7 @@ int main(int argc, char *argv[])
 
 #if defined(Q_OS_LINUX)
   	// Set window icon on Linux using system icon theme
-  	app.setWindowIcon(QIcon::fromTheme("com.github.iwalton3.jellyfin-media-player"));
+  	app.setWindowIcon(QIcon::fromTheme("com.github.iwalton3.jellyfin-media-player", QIcon(":/images/icon.png")));
 #endif
 
 #if defined(Q_OS_MAC) && defined(NDEBUG)