[ic] [interchange] Fix potential "use of uninitialized value" if called during startup

[Peter]

On 23/06/17 19:20, Stefan Hornburg (Racke) wrote:
> 
> Hallo David,
> 
> thanks very much on your effort to clean up Interchange!
> 
> I think the // operator isn't present in older Perls.
> 
>> +		$pat = $Global::AllowedFileRegex->{$Vend::Cat // ''}

Good catch, yeah, it needs to be changed to:
$pat = $Global::AllowedFileRegex->{defined $Vend::Cat ? $Vend::Cat : ''}


Peter