add check on evaluateJavaScript("document.title"

iOSClient/Library/SwiftWebVC/SwiftWebVC.swift

@@ -323,7 +323,7 @@ extension SwiftWebVC: WKNavigationDelegate {
         
         webView.evaluateJavaScript("document.title", completionHandler: {(response, error) in
             if error == nil {
-                if (response != nil) {
+                if (response != nil && response is String) {
                     self.navBarTitle.text = response as! String?
                 }
                 self.navBarTitle.sizeToFit()