fix(router): throw when cannot parse a url

modules/@angular/router/test/url_serializer.spec.ts

@@ -148,6 +148,7 @@ describe('url serializer', () => {
     expect(url.serialize(tree)).toEqual('/one#two');
   });
 
+
   it('should parse empty fragment', () => {
     const tree = url.parse('/one#');
     expect(tree.fragment).toEqual('');
@@ -183,6 +184,17 @@ describe('url serializer', () => {
       expect(url.serialize(tree)).toEqual(u);
     });
   });
+
+  describe('error handling', () => {
+    it('should throw when invalid characters inside children', () => {
+      expect(() => url.parse('/one/(left#one)'))
+          .toThrowError('Cannot parse url \'/one/(left#one)\'');
+    });
+
+    it('should throw when missing closing )', () => {
+      expect(() => url.parse('/one/(left')).toThrowError('Cannot parse url \'/one/(left\'');
+    });
+  });
 });
 
 function expectSegment(segment: UrlSegment, expected: string, hasChildren: boolean = false): void {