[FIX] web_editor: patch for null selection in condition

Reproduction:

1. Go to any record with a chatter
2. Open full composer
3. Enter a special case for the text using shortcuts (CTRL+I for italic,
CTRL+B for bold, etc)
4. exit the special case with the same shortcut
5. JS error

Reason:
A selection is not null check is missing in the condition

Related PR: https://github.com/odoo/odoo/pull/136777

closes odoo/odoo#137499

X-original-commit: db0325503576d06521ab65a64d3c9cce837e66bc
Signed-off-by: David Monjoie (dmo) <dmo@odoo.com>
Signed-off-by: Jinjiu Liu (jili) <jili@odoo.com>

addons/web_editor/static/src/js/editor/odoo-editor/src/utils/utils.js

@@ -741,7 +741,7 @@ export function getSelectedNodes(editable) {
  */
 export function getDeepRange(editable, { range, sel, splitText, select, correctTripleClick } = {}) {
     sel = sel || editable.parentElement && editable.ownerDocument.getSelection();
-    if (sel.isCollapsed && sel.anchorNode && sel.anchorNode.nodeName === "BR") {
+    if (sel && sel.isCollapsed && sel.anchorNode && sel.anchorNode.nodeName === "BR") {
         setCursorStart(sel.anchorNode.parentElement, false);
     }
     range = range ? range.cloneRange() : sel && sel.rangeCount && sel.getRangeAt(0).cloneRange();