The FsShell commands have no standard format for the same error message. For instance, here is a snippet of the variations of just one of many error messages:
cmd: $path: No such file or directory
cmd: cannot stat `$path': No such file or directory
cmd: Can not find listing for $path
cmd: Cannot access $path: No such file or directory.
cmd: No such file or directory `$path'
cmd: File does not exist: $path
cmd: File $path does not exist
... etc ...
These need to be common.