This is how I'd write the sample code rewritten using JRErr. I think it's clean and concise, and doesn't need any tricks. (Not tested, may have bugs ;))

example.m

- (BOOL)incrementBuildNumberInFile:(NSURL *)fileURL error:(NSError **)error
{
    BOOL result = NO;
    static NSString * const sErrorDescription = @"Unrecognized File Format";
    static NSString * const sBuildNumberKey = @"BuildNumber";
    NSError *localError = nil;

    NSData *fileData = [NSData dataWithContentsOfURL:fileURL options:0 error:&localError];
    if (fileData)
    {
        localError = nil;
        NSMutableDictionary *fileDict = [NSPropertyListSerialization propertyListWithData:fileData options:NSPropertyListMutableContainers format:NULL error:&localError];
        if (fileDict)
        {
            NSNumber *buildNumber = [fileDict objectForKey:sBuildNumberKey];
            if (buildNumber)
            {
                if ([buildNumber isKindOfClass:[NSNumber class]])
                {
                    buildNumber = @([buildNumber intValue] + 1);
                    fileDict[sBuildNumberKey] = buildNumber;
                    localError = nil;
                    fileData = [NSPropertyListSerialization dataWithPropertyList:fileDict format:NSPropertyListXMLFormat_v1_0 options:0 error:&localError];
                    if (fileData)
                    {
                        localError = nil;
                        result = [fileData writeToURL:fileURL options:NSDataWritingAtomic error:&localError];
                    }
                }
                else
                {
                    NSString *errReason = @"BuildNumber isn't a Number";
                    NSDictionary *userInfo = @{NSLocalizedDescriptionKey: sErrorDescription, NSLocalizedFailureReasonErrorKey: errReason};
                    localError = [NSError errorWithDomain:@"MyClass" code:-1 userInfo:userInfo];
                }
            }
            else
            {
                NSString *errReason = @"BuildNumber is missing";
                NSDictionary *userInfo = @{NSLocalizedDescriptionKey:sErrorDescription, NSLocalizedFailureReasonErrorKey: errReason};
                localError = [NSError errorWithDomain:@"MyClass" code:-1 userInfo:userInfo];
            }
        }
    }

    if (!result && localError && error)
    {
        NSLog(@"error: %@", localError);
        *error = localError;
    }
    return result;
}