[dconf-editor] GtkBin get_child() is nullable.

[Arnaud Bonatti <arnaudb src gnome org>]

commit 6767e251ab843c424ad3541c9ccdcc698942a23c
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Thu Dec 7 23:47:40 2017 +0100

    GtkBin get_child() is nullable.

 editor/registry-search.vala |    8 ++++----
 editor/registry-view.vala   |    6 +++---
 2 files changed, 7 insertions(+), 7 deletions(-)
---
diff --git a/editor/registry-search.vala b/editor/registry-search.vala
index 3a4ef19..cc12b88 100644
--- a/editor/registry-search.vala
+++ b/editor/registry-search.vala
@@ -34,10 +34,10 @@ class RegistrySearch : Grid, PathElement, BrowsableView
         set
         {
             _small_keys_list_rows = value;
-            key_list_box.foreach((row) => {
-                    Widget row_child = ((ListBoxRow) row).get_child ();
-                    if (row_child is KeyListBoxRow)
-                        ((KeyListBoxRow) row_child).small_keys_list_rows = value;
+            key_list_box.foreach ((row) => {
+                    Widget? row_child = ((ListBoxRow) row).get_child ();
+                    if (row_child != null && (!) row_child is KeyListBoxRow)
+                        ((KeyListBoxRow) (!) row_child).small_keys_list_rows = value;
                 });
         }
     }
diff --git a/editor/registry-view.vala b/editor/registry-view.vala
index 4c0bee9..29d96bf 100644
--- a/editor/registry-view.vala
+++ b/editor/registry-view.vala
@@ -38,9 +38,9 @@ class RegistryView : Grid, PathElement, BrowsableView
         {
             _small_keys_list_rows = value;
             key_list_box.foreach((row) => {
-                    Widget row_child = ((ListBoxRow) row).get_child ();
-                    if (row_child is KeyListBoxRow)
-                        ((KeyListBoxRow) row_child).small_keys_list_rows = value;
+                    Widget? row_child = ((ListBoxRow) row).get_child ();
+                    if (row_child != null && (!) row_child is KeyListBoxRow)
+                        ((KeyListBoxRow) (!) row_child).small_keys_list_rows = value;
                 });
         }
     }