webui: fix client-side nav back button
diff --git a/webui/src/web-components/sketch-app-shell.ts b/webui/src/web-components/sketch-app-shell.ts
index dc3bb6e..9b3430d 100644
--- a/webui/src/web-components/sketch-app-shell.ts
+++ b/webui/src/web-components/sketch-app-shell.ts
@@ -361,6 +361,7 @@
 
     // Binding methods to this
     this._handleViewModeSelect = this._handleViewModeSelect.bind(this);
+    this._handlePopState = this._handlePopState.bind(this);
     this._handleShowCommitDiff = this._handleShowCommitDiff.bind(this);
     this._handleMutlipleChoiceSelected =
       this._handleMutlipleChoiceSelected.bind(this);