Crash: [DiffMatchPatch diff_computeFromOldString:andNewString:checkLines:deadline:]

[jleandroperez]

I've managed to isolate a sample set of strings to trigger this crash (when fed directly to the last method in the call chain):

    NSString *longtext = @"あ ご a ご";
    NSString *shorttext = @"ご a ご";

Crashlog:

Thread : Fatal Exception: NSRangeException
0  CoreFoundation                 0x00007fff90fbb244 __exceptionPreprocess + 148
1  libobjc.A.dylib                0x00007fff939bae75 objc_exception_throw + 43
2  CoreFoundation                 0x00007fff90fbb10c +[NSException raise:format:] + 204
3  Foundation                     0x00007fff94ec2ed1 -[NSString substringFromIndex:] + 107
4  Simplenote                     0x0000000100bfb673 -[DiffMatchPatch diff_computeFromOldString:andNewString:checkLines:deadline:] (DiffMatchPatch.m:505)
5  Simplenote                     0x0000000100bfb2d8 -[DiffMatchPatch diff_mainOfOldString:andNewString:checkLines:deadline:] (DiffMatchPatch.m:383)
6  Simplenote                     0x0000000100bfc584 -[DiffMatchPatch diff_bisectSplitOfOldString:andNewString:x:y:deadline:] (DiffMatchPatch.m:903)
7  Simplenote                     0x0000000100bfb8aa -[DiffMatchPatch diff_computeFromOldString:andNewString:checkLines:deadline:] (DiffMatchPatch.m:543)
8  Simplenote                     0x0000000100bfb2d8 -[DiffMatchPatch diff_mainOfOldString:andNewString:checkLines:deadline:] (DiffMatchPatch.m:383)
9  Simplenote                     0x0000000100bfc5a2 -[DiffMatchPatch diff_bisectSplitOfOldString:andNewString:x:y:deadline:] (DiffMatchPatch.m:907)
10 Simplenote                     0x0000000100bfb8aa -[DiffMatchPatch diff_computeFromOldString:andNewString:checkLines:deadline:] (DiffMatchPatch.m:543)
11 Simplenote                     0x0000000100bfb2d8 -[DiffMatchPatch diff_mainOfOldString:andNewString:checkLines:deadline:] (DiffMatchPatch.m:383)
12 Simplenote                     0x0000000100bfc5a2 -[DiffMatchPatch diff_bisectSplitOfOldString:andNewString:x:y:deadline:] (DiffMatchPatch.m:907)
13 Simplenote                     0x0000000100bfb8aa -[DiffMatchPatch diff_computeFromOldString:andNewString:checkLines:deadline:] (DiffMatchPatch.m:543)
14 Simplenote                     0x0000000100bfb2d8 -[DiffMatchPatch diff_mainOfOldString:andNewString:checkLines:deadline:] (DiffMatchPatch.m:383)
15 Simplenote                     0x0000000100c2ee50 -[SPMemberText diff:otherValue:] (SPMemberText.m:64)
16 Simplenote                     0x0000000100c1eb7f -[SPDiffer diffFromDictionary:toObject:] (SPDiffer.m:98)
17 Simplenote                     0x0000000100c2528c __57-[SPIndexProcessor processVersions:bucket:changeHandler:]_block_invoke (SPIndexProcessor.m:247)
18 Simplenote                     0x0000000100c1d8b6 -[SPCoreDataStorage performSafeBlockAndWait:] (SPCoreDataStorage.m:633)
19 Simplenote                     0x0000000100c24b20 -[SPIndexProcessor processVersions:bucket:changeHandler:] (SPIndexProcessor.m:190)
20 Simplenote                     0x0000000100c44c63 __52-[SPWebSocketChannel processVersionsBatchForBucket:]_block_invoke (SPWebSocketChannel.m:641)
21 libdispatch.dylib              0x00007fff915ab1bb _dispatch_call_block_and_release + 12
22 libdispatch.dylib              0x00007fff915a828d _dispatch_client_callout + 8
23 libdispatch.dylib              0x00007fff915aa673 _dispatch_queue_drain + 451
24 libdispatch.dylib              0x00007fff915ab9c1 _dispatch_queue_invoke + 110
25 libdispatch.dylib              0x00007fff915a9f87 _dispatch_root_queue_drain + 75
26 libdispatch.dylib              0x00007fff915ab177 _dispatch_worker_thread2 + 40
27 libsystem_pthread.dylib        0x00007fff9666bef8 _pthread_wqthread + 314
28 libsystem_pthread.dylib        0x00007fff9666efb9 start_wqthread + 13