Fix missing initial theme of linux tray icon

Close #404

CHANGELOG.md

@@ -20,6 +20,9 @@ Release date: TBD
 #### Windows
 - Fixed an issue where an unexpected window appears while install/uninstalling
 
+#### Linux
+- Fixed missing initial theme of tray icon
+
 ----
 
 ## Release v3.5.0

src/common/settings.js

@@ -18,7 +18,7 @@ function loadDefault(version) {
       teams: [],
       hideMenuBar: false,
       showTrayIcon: false,
-      trayIconTheme: '',
+      trayIconTheme: 'light',
       disablewebsecurity: true,
       minimizeToTray: false,
       toggleWindowOnTrayIconClick: false,