fix: returns an appropriate RC code when no more options are left at a particular dialog level; this has the somewhat beneficial side effect of moving up a level in dialog if there is one, although this requires a 'stop' command to be present in at least one of the top-most dialog options.

addons/escoria-core/game/core-scripts/esc/types/esc_dialog.gd

@@ -90,9 +90,17 @@ func run():
 		escoria.dialog_player,
 		"option_chosen"
 	) as ESCDialogOption
-	var rc = option.run()
-	if rc is GDScriptFunctionState:
-		rc = yield(rc, "completed")
-	if rc != ESCExecution.RC_CANCEL:
-		return self.run()
+
+	var rc = ESCExecution.RC_OK
+
+	# If no valid option was returned, it means this level of dialog is done.
+	# If this is the case and the current level of dialog has a parent, it means
+	# it is still yielding and so will be shown again.
+	if option:
+		rc = option.run()
+		if rc is GDScriptFunctionState:
+			rc = yield(rc, "completed")
+		if rc != ESCExecution.RC_CANCEL:
+			return self.run()
+
 	return rc