handle images with no mime types

lib/single-file/single-file-core.js

@@ -272,6 +272,7 @@ this.SingleFileCore = this.SingleFileCore || (() => {
 	// ------------
 	const ESCAPED_FRAGMENT = "_escaped_fragment_=";
 	const EMPTY_DATA_URI = "data:base64,";
+	const EMPTY_IMAGE = "data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==";
 
 	class DOMProcessor {
 		constructor(options, batchRequest) {
@@ -842,6 +843,7 @@ this.SingleFileCore = this.SingleFileCore || (() => {
 	const PREFIX_DATA_URI_AUDIO = "data:audio/";
 	const PREFIX_DATA_URI_VIDEO = "data:video/";
 	const PREFIX_DATA_URI_IMAGE_SVG = "data:image/svg+xml";
+	const PREFIX_DATA_URI_NO_MIMETYPE = "data:;";
 
 	class DomProcessorHelper {
 		static async getFilename(options, content) {
@@ -1034,13 +1036,13 @@ this.SingleFileCore = this.SingleFileCore || (() => {
 					if (resourceURL && resourceURL != baseURI && DomUtil.testValidPath(resourceURL)) {
 						try {
 							const dataURI = await batchRequest.addURL(new URL(resourceURL, baseURI).href);
-							if (dataURI.startsWith(prefixDataURI)) {
+							if (dataURI.startsWith(prefixDataURI) || dataURI.startsWith(PREFIX_DATA_URI_NO_MIMETYPE)) {
 								resourceElement.setAttribute(attributeName, dataURI);
 							} else {
-								resourceElement.setAttribute(attributeName, EMPTY_DATA_URI);
+								resourceElement.setAttribute(attributeName, EMPTY_IMAGE);
 							}
 						} catch (error) {
-							resourceElement.setAttribute(attributeName, EMPTY_DATA_URI);
+							resourceElement.setAttribute(attributeName, EMPTY_IMAGE);
 						}
 					}
 				}
@@ -1073,7 +1075,7 @@ this.SingleFileCore = this.SingleFileCore || (() => {
 								resourceElement.setAttribute(attributeName, "data:image/svg+xml," + content);
 							}
 						} catch (error) {
-							resourceElement.setAttribute(attributeName, EMPTY_DATA_URI);
+							resourceElement.setAttribute(attributeName, EMPTY_IMAGE);
 						}
 					}
 				}
@@ -1088,12 +1090,12 @@ this.SingleFileCore = this.SingleFileCore || (() => {
 					if (resourceURL && resourceURL != baseURI && DomUtil.testValidPath(resourceURL)) {
 						try {
 							let dataURI = await batchRequest.addURL(new URL(resourceURL, baseURI).href);
-							if (!dataURI.startsWith(prefixDataURI)) {
-								resourceElement.setAttribute(attributeName, EMPTY_DATA_URI);
+							if (!dataURI.startsWith(prefixDataURI) && !dataURI.startsWith(PREFIX_DATA_URI_NO_MIMETYPE)) {
+								resourceElement.setAttribute(attributeName, EMPTY_IMAGE);
 							}
 							return dataURI + (srcsetValue.w ? " " + srcsetValue.w + "w" : srcsetValue.d ? " " + srcsetValue.d + "x" : "");
 						} catch (error) {
-							resourceElement.setAttribute(attributeName, EMPTY_DATA_URI);
+							resourceElement.setAttribute(attributeName, EMPTY_IMAGE);
 						}
 					}
 				}));