fixes a guardian communication runtime (#20929)

code/game/gamemodes/miniantags/guardian/guardian.dm

@@ -196,7 +196,7 @@
 		input = stripped_input(src, "Please enter a message to tell your summoner.", "Guardian", "")
 	else
 		input = message
-	if(!input)
+	if(!input || !summoner)
 		return
 
 	// Show the message to the host and to the guardian.

code/game/gamemodes/miniantags/guardian/host_actions.dm

@@ -28,7 +28,7 @@
 
 /datum/action/guardian/communicate/Trigger()
 	var/input = stripped_input(owner, "Enter a message to tell your guardian:", "Message", "")
-	if(!input)
+	if(!input || !guardian)
 		return
 
 	// Show the message to our guardian and to host.