test: Fixed test test_Glance_Basic_Close, b=(no-bug), c=split-view

Author: mr-cheffy

src/zen/split-view/ZenViewSplitter.mjs

@@ -1139,6 +1139,7 @@ class ZenViewSplitter extends ZenDOMOperatedFeature {
    * Deactivates the split view.
    */
   deactivateCurrentSplitView() {
+    if (this.currentView < 0) return;
     this.setTabsDocShellState(this._data[this.currentView].tabs, false);
     for (const tab of this._data[this.currentView].tabs) {
       const container = tab.linkedBrowser.closest('.browserSidebarContainer');