improved fallback procedure

Former-commit-id: 90807fc649112c0c9f6b2edf5dfd8fe44bd0fed5

lib/single-file/single-file-util.js

@@ -215,7 +215,11 @@ this.singlefile.lib.util = this.singlefile.lib.util || (() => {
 				}
 				try {
 					if (options.frameId) {
-						response = await fetchFrameResource(resourceURL, options.frameId);
+						try {
+							response = await fetchFrameResource(resourceURL, options.frameId);
+						} catch (error) {
+							response = await fetchResource(resourceURL);
+						}
 					} else {
 						response = await fetchResource(resourceURL);
 					}