fix select2#1404 allow formatnomatches to be null in multiselects

Author: ivaynberg

select2.js

@@ -543,7 +543,7 @@ the specific language governing permissions and limitations under the Apache Lic
     function checkFormatter(formatter, formatterName) {
         if ($.isFunction(formatter)) return true;
         if (!formatter) return false;
-        throw new Error("formatterName must be a function or a falsy value");
+        throw new Error(formatterName +" must be a function or a falsy value");
     }
 
     function evaluate(val) {
@@ -2814,7 +2814,9 @@ the specific language governing permissions and limitations under the Apache Lic
             //If all results are chosen render formatNoMAtches
             if(!this.opts.createSearchChoice && !choices.filter('.select2-result:not(.select2-selected)').length > 0){
             	if(!data || data && !data.more && this.results.find(".select2-no-results").length === 0) {
-            	    this.results.append("<li class='select2-no-results'>" + self.opts.formatNoMatches(self.search.val()) + "</li>");
+            	    if (checkFormatter(self.opts.formatNoMatches, "formatNoMatches")) {
+                        this.results.append("<li class='select2-no-results'>" + self.opts.formatNoMatches(self.search.val()) + "</li>");
+                    }
             	}
             }