Here we have way more cause to error. 

In this case I would say that an error on one line would make the diff unusable, so let's change the method declaration to be:

`- (BOOL)enumerateLinesInHunkWithError:(NSError **)error usingBlock:(void (^)(GTDiffLine *line, BOOL *stop))block`

Then, if we encounter an error here, we can bail out of the enumeration by setting `error` and returning `NO`.