Fix default value syntax

Author: victorneuret

lib/index.js

@@ -931,7 +931,10 @@ MapboxGeocoder.prototype = {
    * @param {boolean} [showSuggestions=false] display suggestion on setInput call
    * @returns {MapboxGeocoder} this
    */
-  setInput: function(searchInput, showSuggestions = true) {
+  setInput: function(searchInput, showSuggestions) {
+    if (showSuggestions === undefined) {
+      showSuggestions = false
+    }
     // Set input value to passed value and clear everything else.
     this._inputEl.value = searchInput;
     this._typeahead.selected = null;