Only look for target disk during Upload (#21804)

Marlin/src/HAL/LPC1768/upload_extra_script.py

@@ -20,7 +20,8 @@ def print_error(e):
 		  'or copy the firmware (.pio/build/%s/firmware.bin) manually to the appropriate disk\n' \
 		  %(e, env.get('PIOENV')))
 
-try:
+def before_upload(source, target, env):
+	try:
 		#
 		# Find a disk for upload
 		#
@@ -116,5 +117,7 @@ try:
 		else:
 			print_error('Autodetect Error')
 
-except Exception as e:
+	except Exception as e:
 		print_error(str(e))
+
+env.AddPreAction("upload", before_upload)