Fix blank gene dialog in Pd.deep

Closes #2

layouts/custom/hu.donor.deep.html

@@ -186,7 +186,11 @@
             var genes = {{ index .Site.Data.sc_data.hu_donor_pr_deep.genes }};
             _gene = $("#gene").val().toUpperCase();
             if ($.inArray(_gene, genes.genes) < 0) {
-                alert("Gene " + _gene + " not exist in the data.")
+                if (_gene == "") {
+                    alert("No Gene Selected.")
+                } else {
+                    alert("Gene " + _gene + " not exist in the data.")
+                }
                 return
             }
             document.getElementById("label.gene").innerHTML = _gene