Don't create surfaces with invalid pixel formats

Fixes https://github.com/libsdl-org/SDL/issues/12556

src/video/SDL_surface.c

@@ -204,6 +204,11 @@ SDL_Surface *SDL_CreateSurface(int width, int height, SDL_PixelFormat format)
         return NULL;
     }
 
+    if (format == SDL_PIXELFORMAT_UNKNOWN) {
+        SDL_InvalidParamError("format");
+        return NULL;
+    }
+
     if (!SDL_CalculateSurfaceSize(format, width, height, &size, &pitch, false /* not minimal pitch */)) {
         // Overflow...
         return NULL;
@@ -250,6 +255,11 @@ SDL_Surface *SDL_CreateSurfaceFrom(int width, int height, SDL_PixelFormat format
         return NULL;
     }
 
+    if (format == SDL_PIXELFORMAT_UNKNOWN) {
+        SDL_InvalidParamError("format");
+        return NULL;
+    }
+
     if (pitch == 0 && !pixels) {
         // The application will fill these in later with valid values
     } else {