Add corruption check for Mach-O files into fileinfo

In #281, a corruption check of PE files was added into `fileinfo`. What this check does is that it verifies whether the input PE file is loadable by the Windows loader, and presents this piece of information to the user:
```
"loaderError" :
{
"code" : 9,
"code_text" : "LDR_ERROR_NO_OPTHDR_MAGIC",
"description" : "Invalid IMAGE_OPTIONAL_HEADER::Magic"
},
```
Would it be possible to add a similar check for Mach-O files?

Start by reading the existing PE corruption check referenced in #281 and trace how fileinfo handles Mach-O inputs. Identify the relevant validation entry point and the existing user-facing result format before determining the equivalent Mach-O behavior. Done means fileinfo reports Mach-O corruption consistently; the issue names no test, so locate or add coverage around the discovered check.

Written by the indexing model from the issue text.