A layer object may be instantiated when setting a combine mode, but before a
texture is associated. (e.g. this is done by the pango renderer) if this is the
case we shouldn't call cogl_texture_get_format() with an invalid cogl handle.
This patch skips over layers without a texture handle when determining if any
textures have an alpha channel.
for (tmp = material->layers; tmp != NULL; tmp = tmp->next)
{
CoglMaterialLayer *layer = tmp->data;
+
+ /* NB: A layer may have a combine mode set on it but not yet have an
+ * associated texture. */
+ if (!layer->texture)
+ continue;
+
if (cogl_texture_get_format (layer->texture) & COGL_A_BIT)
material->flags |= COGL_MATERIAL_FLAG_ENABLE_BLEND;
}