feat(Calls): avoid undefined on some properties when call is ended

ui/views/App/Calls/CallsWindow.qml

@@ -22,6 +22,7 @@ Window {
     callError: '',
     isOutgoing: true,
     recording: false,
+    localSas: '',
     sipAddress: '',
     type: false,
     updating: true,

ui/views/App/Calls/Incall.js

@@ -87,7 +87,7 @@ function handleVideoRequested () {
 }
 
 function makeReadableSecuredString (securedString) {
-  if (!securedString.length) {
+  if (!securedString || !securedString.length) {
     return qsTr('callNotSecured')
   }