[librsvg/librsvg-2.44] Handle child being in error in feLighting

[Federico Mena Quintero <federico src gnome org>]

commit 81d97908c334ea99c7f1f6364b117254242ec170
Author: Ivan Molodetskikh <yalterz gmail com>
Date:   Tue Sep 25 11:40:04 2018 +0300

    Handle child being in error in feLighting

 rsvg_internals/src/filters/light/lighting.rs | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/rsvg_internals/src/filters/light/lighting.rs b/rsvg_internals/src/filters/light/lighting.rs
index 33ab1fd5..1e77f882 100644
--- a/rsvg_internals/src/filters/light/lighting.rs
+++ b/rsvg_internals/src/filters/light/lighting.rs
@@ -236,6 +236,10 @@ impl Filter for Lighting {
         }
 
         let light_source = light_source.unwrap();
+        if light_source.is_in_error() {
+            return Err(FilterError::ChildNodeInError);
+        }
+
         let light_source = light_source.get_impl::<LightSource>().unwrap();
         let light_source = light_source.transform(ctx);