address errors

Author: jay-kunaico

src/react-image-lightbox.js

@@ -1903,15 +1903,15 @@ ReactImageLightbox.defaultProps = {
   prevButtonImage: null,
   closeButtonImage: null,
   thumbnailImages: [],
-  closeButtonComponent: () => {},
+  closeButtonComponent: null,
   closeButtonComponentProps: {},
-  directionalButtonComponent: () => {},
+  directionalButtonComponent: null,
   directionalButtonComponentProps: {},
-  imageHeaderComponent: () => {},
+  imageHeaderComponent: null,
   maxHeightOffset: 0,
   maxWidthOffset: 0,
-  thumbnailArrowLeft: () => {},
-  thumbnailArrowRight: () => {},
+  thumbnailArrowLeft: null,
+  thumbnailArrowRight: null,
   widthBreakPoint: 960,
 };