minor refactoring

Former-commit-id: 7906b39e21357f2b136aaae4495312662731c2ab

lib/single-file/modules/html-images-alt-minifier.js

@@ -32,11 +32,9 @@ this.singlefile.lib.modules.imagesAltMinifier = this.singlefile.lib.modules.imag
 			doc.querySelectorAll("picture").forEach(pictureElement => {
 				const imgElement = pictureElement.querySelector("img");
 				if (imgElement) {
-					let srcData = getImgSrcData(imgElement);
-					let { src, srcset } = srcData;
+					let { src, srcset } = getImgSrcData(imgElement);
 					if (!src) {
-						const sources = Array.from(pictureElement.querySelectorAll("source")).reverse();
-						const data = getSourceSrcData(Array.from(sources));
+						const data = getSourceSrcData(Array.from(pictureElement.querySelectorAll("source")).reverse());
 						src = data.src;
 						if (!srcset) {
 							srcset = data.srcset;