workaround for Array builtin call on proxied array

Calling the builtin function 'sort' on an array wrapped in an ES6
proxy results in "illegal access" being thrown (a string, not an
Error). This is probably related in some way to these issues:
tvcutsem/harmony-reflect#6
tvcutsem/harmony-reflect#19

This change fixes the problem for the time being through a rather
explicit workaround; if the issue also occurs for other functions, it
will likely surface again.
(also, the change in Session.js makes sure error log entry is nicely
formatted even when strings are thrown)

src/comm/Session.js

@@ -297,9 +297,14 @@ Session.prototype.postRequestProc = function postRequestProc(req) {
 Session.prototype.handleAmfReqError = function handleAmfReqError(err, req) {
 	if (typeof err === 'object' && err.type === 'stack_overflow') {
 		// special treatment for stack overflow errors
-		// see <https://github.com/trentm/node-bunyan/issues/127>
+		// see https://github.com/trentm/node-bunyan/issues/127
 		err = new Error(err.message);
 	}
+	if (typeof err === 'string') {
+		// catch malcontents throwing strings instead of Errors, e.g.
+		// https://github.com/tvcutsem/harmony-reflect/issues/38
+		err = new Error(err);
+	}
 	log.error(err, 'error processing %s request for %s', req.type, this.pc);
 	if (this.pc && req.id) {
 		// send error response back to client

src/data/persProxy.js

@@ -40,6 +40,12 @@ function makeProxy(obj, prop) {
 			if (name === '__isPP') {
 				return true;
 			}
+			if (name === 'sort' && typeof target.sort === 'function' &&
+				target instanceof Array) {
+				// workaround for builtin Array.prototype.sort (calling it on a
+				// proxied array throws "illegal access" string otherwise)
+				return target.sort.bind(target);
+			}
 			if (name === 'valueOf' || name === 'toString') {
 				return function () {
 					return '^P' + target.toString();

test/unit/data/persProxy.js

@@ -138,5 +138,14 @@ suite('persProxy', function () {
 			assert.strictEqual(JSON.stringify(p),
 				'{"tsid":"x","arr":[{"x":3},[1,2,3]]}');
 		});
+
+		test('pproxy does not break Array.sort', function () {
+			var arr = ['alph', 'humbaba', 'cosma', 'spriggan'];
+			var p = pp.makeProxy(arr);
+			var sorted = p.sort(function (a, b) {
+				return a < b;
+			});
+			assert.deepEqual(sorted, ['spriggan', 'humbaba', 'cosma', 'alph']);
+		});
 	});
 });