More robust infinite recursion handling with custom exception (#7882)

* Introduced preliminary idea for infinite recurse exception

* Better handling of infinite recursion

But it could be better still...

* the TransclusionError is a proper error

Moved the magic number to be on the error's class. Not sure if that's
a great idea.

* Fixed minor minor issue that came up in conflict

The minor fix to the jasmine regexp that escaped a '+' somehow
broke some random test.

core/modules/utils/errors.js

@@ -0,0 +1,23 @@
+/*\
+title: $:/core/modules/utils/errors.js
+type: application/javascript
+module-type: utils
+
+Custom errors for TiddlyWiki.
+
+\*/
+(function(){
+
+function TranscludeRecursionError() {
+	Error.apply(this,arguments);
+	this.signatures = Object.create(null);
+};
+
+/* Maximum permitted depth of the widget tree for recursion detection */
+TranscludeRecursionError.MAX_WIDGET_TREE_DEPTH = 1000;
+
+TranscludeRecursionError.prototype = Object.create(Error);
+
+exports.TranscludeRecursionError = TranscludeRecursionError;
+
+})();