Fix T92934: crash rendering with wrong image path

These null checks were missing in rB0c3b215e7d5456878b155d13440864f49ad1f230.

Differential Revision: https://developer.blender.org/D13157

source/blender/blenkernel/intern/image.c

@@ -1304,6 +1304,9 @@ void BKE_image_print_memlist(Main *bmain)
 
 static bool imagecache_check_dirty(ImBuf *ibuf, void *UNUSED(userkey), void *UNUSED(userdata))
 {
+  if (ibuf == NULL) {
+    return false;
+  }
   return (ibuf->userflags & IB_BITMAPDIRTY) == 0;
 }
 
@@ -1347,6 +1350,9 @@ void BKE_image_free_all_textures(Main *bmain)
 
 static bool imagecache_check_free_anim(ImBuf *ibuf, void *UNUSED(userkey), void *userdata)
 {
+  if (ibuf == NULL) {
+    return true;
+  }
   int except_frame = *(int *)userdata;
   return (ibuf->userflags & IB_BITMAPDIRTY) == 0 && (ibuf->index != IMA_NO_INDEX) &&
          (except_frame != IMA_INDEX_ENTRY(ibuf->index));

source/blender/imbuf/intern/moviecache.c

@@ -237,6 +237,9 @@ static int get_item_priority(void *item_v, int default_priority)
 static bool get_item_destroyable(void *item_v)
 {
   MovieCacheItem *item = (MovieCacheItem *)item_v;
+  if (item->ibuf == NULL) {
+    return true;
+  }
   /* IB_BITMAPDIRTY means image was modified from inside blender and
    * changes are not saved to disk.
    *