$c->req->body_data dies internally for JSON request with empty HTTP message body

[dboehmer]

I was investigating an issue in our app until I realized there is a bug in Catalyst itself.

How to reproduce:

• have an app read $c->req->body_data—I tried this with a fresh app created by catalyst.pl by just adding that call to the default action method
• send invalid JSON like this:

curl -v --json '' http://localhost:3000/

Actual result:

[error] Error Parsing POST 'undef', Error: Can't locate object method "getline" via package "0" (perhaps you forgot to load "0"?) at .../perlbrew/perls/perl-5.38.0-threads-bullseye/lib/site_perl/5.38.0/Catalyst.pm line 4091.

Expected result:

• either return (); or a catchable exception from parsing the empty string

I think Pull Request #186 solves part of the problem related with repeated calls on $c->req->body_data but with that the code already fails on $fh->seek (see my comment there). Currently the data handler fails for $fh->getline.

Should the data handler always receive a filehandle, possibly an empty one, or does every data handler need to check whether a filehandle is present first?