don't allow to add gene mapping if genome is not defined

CHANGELOG

+minerva (13.1.1) stable; urgency=medium
+  * Bug fix: adding gene mapping before the genome caused an error (#835)
+
+ -- Piotr Gawron <piotr.gawron@uni.lu>  Fri, 28 Jun 2019 17:00:00 +0200
+
 minerva (13.1.0) stable; urgency=medium
   * Feature: annotators are more flexible - you can define set of input and
     outputs used by annotator (#617)

frontend-js/src/main/js/gui/admin/EditGenomeDialog.js

@@ -175,7 +175,8 @@ EditGenomeDialog.prototype.createGeneMappingTabContent = function () {
 
   var result = Functions.createElement({
     type: "div",
-    style: "margin-top:10px;"
+    style: "margin-top:10px;",
+    className: "minerva-gene-mapping-tab"
   });
 
   var geneMappingTable = Functions.createElement({
@@ -513,6 +514,10 @@ EditGenomeDialog.prototype.refresh = function () {
     //it should be simplified, but I couldn't make it work
     dataTable.clear().rows.add(data).page(page).draw(false).page(page).draw(false);
 
+    if (self.isNew()) {
+      guiUtils.disableTab($(".minerva-gene-mapping-tab", self.getElement())[0], "First add a genome to be able to add mapping");
+    }
+
     return self._fillOrganismSelect(genome);
   });
 };