[gnome-builder] sourceview: ensure we have a valid completion object first

[Christian Hergert <chergert src gnome org>]

commit a4cf749947984939e9697957ea0fb95a3e1045db
Author: Christian Hergert <chergert redhat com>
Date:   Fri Aug 9 14:55:00 2019 -0700

    sourceview: ensure we have a valid completion object first

 src/libide/sourceview/ide-source-view.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/libide/sourceview/ide-source-view.c b/src/libide/sourceview/ide-source-view.c
index 3e76549a1..ce10cd4b7 100644
--- a/src/libide/sourceview/ide-source-view.c
+++ b/src/libide/sourceview/ide-source-view.c
@@ -5524,7 +5524,8 @@ ide_source_view_set_property (GObject      *object,
       break;
 
     case PROP_COMPLETION_N_ROWS:
-      ide_completion_set_n_rows (priv->completion, g_value_get_uint (value));
+      if (priv->completion != NULL)
+        ide_completion_set_n_rows (priv->completion, g_value_get_uint (value));
       break;
 
     case PROP_COUNT: