Fix React type warnings

src/components/inputs/AutocompleteInput.jsx

@@ -6,10 +6,15 @@ import { margins, fontSizes } from '../../config/scales'
 
 class AutocompleteInput extends React.Component {
   static propTypes = {
-    value: React.PropTypes.string.isRequired,
+    value: React.PropTypes.string,
-    options: React.PropTypes.array.isRequired,
+    options: React.PropTypes.array,
     style: React.PropTypes.object,
-    onChange: React.PropTypes.func.isRequired,
+    onChange: React.PropTypes.func,
+  }
+
+  static defaultProps = {
+    onChange: () => {},
+    options: [],
   }
 
   render() {

src/components/layers/LayerSourceBlock.jsx

@@ -7,9 +7,14 @@ import AutocompleteInput from '../inputs/AutocompleteInput'
 
 class LayerSourceBlock extends React.Component {
   static propTypes = {
-    value: React.PropTypes.string.isRequired,
+    value: React.PropTypes.string,
-    onChange: React.PropTypes.func.isRequired,
+    onChange: React.PropTypes.func,
-    sourceIds: React.PropTypes.array.isRequired,
+    sourceIds: React.PropTypes.array,
+  }
+
+  static defaultProps = {
+    onChange: () => {},
+    sourceIds: [],
   }
 
   render() {

src/components/layers/LayerSourceLayerBlock.jsx

@@ -7,9 +7,14 @@ import AutocompleteInput from '../inputs/AutocompleteInput'
 
 class LayerSourceLayer extends React.Component {
   static propTypes = {
-    value: React.PropTypes.string.isRequired,
+    value: React.PropTypes.string,
-    onChange: React.PropTypes.func.isRequired,
+    onChange: React.PropTypes.func,
-    sourceLayerIds: React.PropTypes.array.isRequired,
+    sourceLayerIds: React.PropTypes.array,
+  }
+
+  static defaultProps = {
+    onChange: () => {},
+    sourceLayerIds: [],
   }
 
   render() {