ensure the lazy-loaded image is bigger than the placeholder

lib/single-file/lazy-loader.js

@@ -74,7 +74,7 @@ this.lazyLoader = this.lazyLoader || (() => {
 	function replaceSrc(elements, attributeName, propertyName) {
 		elements.forEach(element => {
 			const dataSrc = element.dataset[propertyName || attributeName];
-			if (dataSrc && dataSrc.startsWith(DATA_URI_PREFIX) && dataSrc != EMPTY_DATA_URI && element.src != dataSrc) {
+			if (dataSrc && dataSrc.startsWith(DATA_URI_PREFIX) && dataSrc != EMPTY_DATA_URI && (!element.src || (element.src != dataSrc && dataSrc.length > element.src.length))) {
 				element.src = element.dataset[propertyName || attributeName];
 				processElement(element);
 				element.style.opacity = 1;