SDL: SDL_pen.c: release pen mutex on error return

SDL Commits
1 
From 6d37f4798e4d957ffd8e8ef9059cdebb2b323c92 Mon Sep 17 00:00:00 2001
From: Christoph Reichenbach <[EMAIL REDACTED]>
Date: Thu, 28 Mar 2024 20:37:54 +0000
Subject: [PATCH] SDL_pen.c: release pen mutex on error return

---
 src/events/SDL_pen.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/events/SDL_pen.c b/src/events/SDL_pen.c
index ed15c31004a2b..e1d69115b3235 100644
--- a/src/events/SDL_pen.c
+++ b/src/events/SDL_pen.c
@@ -74,6 +74,7 @@ static SDL_GUID pen_guid_zero = { { 0 } };
     penvar = SDL_GetPenPtr(instance_id);          \
     if (!(penvar)) {                              \
         SDL_SetError("Stale SDL_PenID");          \
+        SDL_UNLOCK_PENS();                        \
         return (err_return);                      \
     }