Jerry,
I couldn't replicate the exception you saw. I created a unit test to read the Google Chrome bookmark from a file into a string, then create a dictionary from it. It all worked fine for me with the tip of my fork (that sounds a little naughty).
http://github.com/billgarrison/bsjsonadditions
Here's the test I used (added to NSDictionary_UnitTests.m).
- (void) testParseGoogleChromeBookmarks
{
NSBundle *unitTestBundle = [NSBundle bundleForClass:[self class]];
NSString *testFile = [unitTestBundle pathForResource:@"google-chrome-bookmarks" ofType:@"json"];
STAssertNotNil( testFile, @"Can't locate data file for this test");
NSError *error = nil;
NSString *encoded = [NSString stringWithContentsOfFile:testFile encoding:NSUTF8StringEncoding error:&error];
STAssertNotNil( encoded, @"Error reading test data: %@", error);
NSDictionary *decodedDict = [NSDictionary dictionaryWithJSONString:encoded];
STAssertNotNil( decodedDict, @"Couldn't decode Gooogle Chrome bookmarks file");
}
And the data file.