refactor: Add LAST_CAST_ADDRESS and streamline subprocess error handling

main.py

@@ -6,8 +6,8 @@ logging.basicConfig(
 
 from flask import Flask, request
 
-# Constants
 AUTO_STOP_TIMEOUT_SECONDS = 3600  # 1 hour
+LAST_CAST_ADDRESS = None
 
 app = Flask(__name__)
 auto_stop_timer = None # Timer for automatic VNC stop
@@ -63,10 +63,6 @@ def cast_machine(ip_address):
         # Use Popen to run the command in the background (non-blocking)
         subprocess.Popen(command, shell=True)
         logging.info(f"Command '{command}' launched successfully.")
-    except FileNotFoundError:
-        # This error is more likely if the shell itself (e.g., /bin/sh) is not found,
-        # or if 'xtightvncviewer' is not in PATH and the shell fails to find it.
-        logging.error(f"Failed to launch VNC for {ip_address}: Shell or VNC command might not be found. Ensure xtightvncviewer is in PATH and shell is available.")
     except Exception as e: # Catch other potential errors during Popen
         logging.error(f"An error occurred while launching VNC for {ip_address} with Popen: {e}")
 
@@ -87,8 +83,6 @@ def kill_vnc():
             if "no process found" in result.stderr.lower():
                  logging.info("No xtightvncviewer processes were found to kill.")
 
-    except FileNotFoundError:
-        logging.error(f"Command not found: killall. Please ensure it is installed and in PATH.")
     except Exception as e:
         logging.error(f"An unexpected error occurred while trying to run killall: {e}")