fixed issue when a URL is pointing to a hash of the (SVG) document

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

@@ -1211,7 +1211,7 @@ this.SingleFileCore = this.SingleFileCore || (() => {
 				const originalResourceURL = Util.matchURL(urlFunction);
 				const resourceURL = Util.normalizeURL(originalResourceURL);
 				if (!Util.testIgnoredPath(resourceURL)) {
-					if (Util.testValidPath(resourceURL, baseURI, options.url)) {
+					if (!resourceURL || Util.testValidPath(resourceURL, baseURI, options.url)) {
 						let resolvedURL;
 						try {
 							resolvedURL = DocUtil.resolveURL(resourceURL, baseURI);