Suppress error window on Linux platform when daemon thread terminated

Signed-off-by: Loren Eteval <loren.eteval@proton.me>

Furious/__main__.py

@@ -25,6 +25,12 @@ def main():
 
         exitcode = process.exitcode
 
+        if exitcode == -6:
+            # On Linux platform, daemon thread(filesystem events listener thread)
+            # terminated and result in application exitcode -6. Make it as exit
+            # success thus error window won't show.
+            exitcode = 0
+
         if exitcode == 0:
             sys.exit(exitcode)