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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * The 3 methods here are duplicated from ThreadSafeDevToolsUtils.js
+ * The ones defined here are used from other sys.mjs files, mostly from the
+ * NetworkObserver codebase, while the ones remaining in ThreadSafeDevToolsUtils.js
+ * are used in commonjs modules, including modules which can be loaded in workers.
+ *
+ * sys.mjs modules are currently not supported in workers, see Bug 1247687.
+ */
+
+/**
+ * Report that |who| threw an exception, |exception|.
+ */
+function reportException(who, exception) {
+ const msg = `${who} threw an exception: ${safeErrorString(exception)}`;
+ dump(msg + "\n");
+
+ if (typeof console !== "undefined" && console && console.error) {
+ console.error(exception);
+ }
+}
+
+/**
+ * Given a handler function that may throw, return an infallible handler
+ * function that calls the fallible handler, and logs any exceptions it
+ * throws.
+ *
+ * @param handler function
+ * A handler function, which may throw.
+ * @param aName string
+ * A name for handler, for use in error messages. If omitted, we use
+ * handler.name.
+ *
+ * (SpiderMonkey does generate good names for anonymous functions, but we
+ * don't have a way to get at them from JavaScript at the moment.)
+ */
+function makeInfallible(handler, name = handler.name) {
+ return function () {
+ try {
+ return handler.apply(this, arguments);
+ } catch (ex) {
+ let who = "Handler function";
+ if (name) {
+ who += " " + name;
+ }
+ reportException(who, ex);
+ return undefined;
+ }
+ };
+}
+
+/**
+ * Turn the |error| into a string, without fail.
+ *
+ * @param {Error|any} error
+ */
+function safeErrorString(error) {
+ try {
+ let errorString = error.toString();
+ if (typeof errorString == "string") {
+ // Attempt to attach a stack to |errorString|. If it throws an error, or
+ // isn't a string, don't use it.
+ try {
+ if (error.stack) {
+ const stack = error.stack.toString();
+ if (typeof stack == "string") {
+ errorString += "\nStack: " + stack;
+ }
+ }
+ } catch (ee) {
+ // Ignore.
+ }
+
+ // Append additional line and column number information to the output,
+ // since it might not be part of the stringified error.
+ if (
+ typeof error.lineNumber == "number" &&
+ typeof error.columnNumber == "number"
+ ) {
+ errorString +=
+ "Line: " + error.lineNumber + ", column: " + error.columnNumber;
+ }
+
+ return errorString;
+ }
+ } catch (ee) {
+ // Ignore.
+ }
+
+ // We failed to find a good error description, so do the next best thing.
+ return Object.prototype.toString.call(error);
+}
+
+export const DevToolsInfaillibleUtils = {
+ makeInfallible,
+ reportException,
+ safeErrorString,
+};