SDL_rtf: Fix 'retval' may be used uninitialized [-Werror=maybe-uninitialized]

From 5832e3a29971c2b12ff899037c98959a4c699a94 Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <[EMAIL REDACTED]>
Date: Mon, 15 Jan 2024 18:54:08 +0100
Subject: [PATCH] Fix 'retval' may be used uninitialized
 [-Werror=maybe-uninitialized]

---
 src/SDL_rtf.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/SDL_rtf.c b/src/SDL_rtf.c
index b85939e..bb8dd3b 100644
--- a/src/SDL_rtf.c
+++ b/src/SDL_rtf.c
@@ -121,6 +121,10 @@ int RTF_Load_RW(RTF_Context *ctx, SDL_RWops *src, int freesrc)
             RTF_SetError("Couldn't find font for text");
             retval = -1;
             break;
+        default:
+            RTF_SetError("Unknown error");
+            retval = -1;
+            break;
     }
     while ( ctx->psave ) {
         ecPopRtfState(ctx);