[gnome-text-editor] languagedialog: check for placeholder widget

[Christian Hergert <chergert src gnome org>]

commit 43fbd56a3bf2a1663dbf03a4572994a0e6512794
Author: Christian Hergert <chergert redhat com>
Date:   Thu Dec 2 15:34:08 2021 -0800

    languagedialog: check for placeholder widget

 src/editor-language-dialog.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)
---
diff --git a/src/editor-language-dialog.c b/src/editor-language-dialog.c
index eb94663..f0a6571 100644
--- a/src/editor-language-dialog.c
+++ b/src/editor-language-dialog.c
@@ -371,12 +371,15 @@ editor_language_dialog_set_language (EditorLanguageDialog *self,
        child != NULL;
        child = gtk_widget_get_next_sibling (child))
     {
-      EditorLanguageRow *row = EDITOR_LANGUAGE_ROW (child);
-
-      if (language == _editor_language_row_get_language (row))
+      if (EDITOR_IS_LANGUAGE_ROW (child))
         {
-          editor_language_dialog_select (EDITOR_LANGUAGE_DIALOG (self), row);
-          break;
+          EditorLanguageRow *row = EDITOR_LANGUAGE_ROW (child);
+
+          if (language == _editor_language_row_get_language (row))
+            {
+              editor_language_dialog_select (EDITOR_LANGUAGE_DIALOG (self), row);
+              break;
+            }
         }
     }
 }