workaround for FF Private Window mode when cookies are preserved and localStorage is not

CHANGELOG

 minerva (14.0.0~beta.0) unstable; urgency=low
+  * Bug fix: work on FF Private Window mode could cause logout or raise an 
+    error on when opening new tab with minerva (#892)
   * Bug fix: fetching list of miRnas resulted sometimes in "Internal Server 
     Error" (#889)
   * Bug fix: user without admin right can accept terms of service (#893)

frontend-js/src/main/js/ServerConnector.js

@@ -182,7 +182,16 @@ ServerConnector.sendGetRequest = function (url, description) {
 ServerConnector.isSessionValid = function () {
   var self = this;
   return self._sendRequest({method: "GET", url: this.isSessionValidUrl()}).then(function (content) {
-    return JSON.parse(content).login === self.getSessionData(null).getLogin();
+    var sessionLogin = self.getSessionData(null).getLogin();
+    var serverSideLogin = JSON.parse(content).login;
+
+    //this is workaround for the problem with Firefox Private Window issue
+    //in FF new tab is opened with existing cookies but localStorage is cleared
+    if (sessionLogin === undefined || sessionLogin === null) {
+      console.log("SET USER");
+      self.getSessionData(null).setLogin(serverSideLogin);
+    }
+    return serverSideLogin === self.getSessionData(null).getLogin();
   }).catch(function (error) {
     if (error instanceof NetworkError) {
       if (error.statusCode === HttpStatus.FORBIDDEN || error.statusCode === HttpStatus.UNAUTHORIZED) {

frontend-js/src/main/js/SessionData.js

@@ -2,7 +2,6 @@
 
 /* exported logger */
 
-var Point = require('./map/canvas/Point');
 var SessionObjectType = require('./SessionObjectType');
 
 // noinspection JSUnusedLocalSymbols
@@ -307,7 +306,7 @@ SessionData.prototype.setLogin = function (login) {
 
 /**
  *
- * @returns {string}
+ * @returns {?null|string}
  */
 SessionData.prototype.getLogin = function () {
   var key = SessionObjectType.LOGIN;