Fix non existing value warning

src/components/fields/SpecField.jsx

@@ -70,6 +70,7 @@ export default class SpecField extends React.Component {
         if(options.length <= 3 && optionsLabelLength(options) <= 20) {
           return <MultiButtonInput
             {...commonProps}
+            value={this.props.value || this.props.fieldSpec.default}
             options={options}
           />
         } else {

src/components/filter/FilterEditor.jsx

@@ -30,7 +30,7 @@ function hasNestedCombiningFilter(filter) {
 export default class CombiningFilterEditor extends React.Component {
   static propTypes = {
     /** Properties of the vector layer and the available fields */
-    properties: React.PropTypes.object.isRequired,
+    properties: React.PropTypes.object,
     filter: React.PropTypes.array,
     onChange: React.PropTypes.func.isRequired,
   }