property added to handle error

Author: Satyanarayan Dash

README.md

@@ -92,6 +92,7 @@ nextSrcThumbnail    | string |                |          | Thumbnail image url c
 onCloseRequest      | func   |                |    yes   | Close window event. Should change the parent state such that the lightbox is not rendered
 onMovePrevRequest   | func   | empty function |          | Move to previous image event. Should change the parent state such that props.prevSrc becomes props.mainSrc, props.mainSrc becomes props.nextSrc, etc.
 onMoveNextRequest   | func   | empty function |          | Move to next image event. Should change the parent state such that props.nextSrc becomes props.mainSrc, props.mainSrc becomes props.prevSrc, etc.
+onLoadError         | func   | error object   |          | Will listen to the error if image is not loading
 discourageDownloads | bool   | `false`        |          | Enable download discouragement (prevents [right-click -> Save Image As...])
 animationDisabled   | bool   | `false`        |          | Disable all animation
 animationOnKeyInput | bool   | `false`        |          | Disable animation on actions performed with keyboard shortcuts

src/react-image-lightbox.js

@@ -717,7 +717,8 @@ class ReactImageLightbox extends Component {
         const that = this;
         const inMemoryImage = new Image();
 
-        inMemoryImage.onerror = function onError() {
+        inMemoryImage.onerror = () => {
+            this.props.onLoadError(new Error('image load error'));
             callback('image load error');
         };
 
@@ -1236,6 +1237,9 @@ ReactImageLightbox.propTypes = {
     //  props.mainSrc becomes props.prevSrc, etc.
     onMoveNextRequest: PropTypes.func,
 
+    //Listener if any error occurs while loading the image
+    onLoadError: PropTypes.func,
+
     //-----------------------------
     // Download discouragement settings
     //-----------------------------
@@ -1305,6 +1309,7 @@ ReactImageLightbox.propTypes = {
 ReactImageLightbox.defaultProps = {
     onMovePrevRequest: () => {},
     onMoveNextRequest: () => {},
+    onLoadError: () => {},
 
     discourageDownloads: false,