Prevent errors when up/down arrows are pressed in an empty notebook.

Notebook.get_selected_cell() returns `null` in an empty notebook.
13 years ago · 904be21a9f
parent a8873230bf
commit 904be21a9f
1 changed files with 2 additions and 2 deletions
--- a/IPython/frontend/html/notebook/static/js/notebook.js
+++ b/IPython/frontend/html/notebook/static/js/notebook.js
@ -137,13 +137,13 @@ var IPython = (function (IPython) {
            }
            if (event.which === key.UPARROW && !event.shiftKey) {
                var cell = that.get_selected_cell();
-                if (cell.at_top()) {
+                if (cell && cell.at_top()) {
                    event.preventDefault();
                    that.select_prev();
                };
            } else if (event.which === key.DOWNARROW && !event.shiftKey) {
                var cell = that.get_selected_cell();
-                if (cell.at_bottom()) {
+                if (cell && cell.at_bottom()) {
                    event.preventDefault();
                    that.select_next();
                };