Well.. not exactly it, but put me on track to finding it.

It didn't like the "\$p->{$vn}".

Once I fixed that, the error kicked up to the calling routine, which "was":

  sub _access_maker {       #{{{
    my $pkg  = shift;      #var in $_
    {
      my $proc = '# line ' . __LINE__ . ' "' . __FILE__ . "\"\n" . '
      { use warnings;use strict;
        package '.$pkg.'; 
        sub '.$_.' (;$) :lvalue {
          unshift @_, [shift, Data::Vars::varname((caller 0)[3]), want
+array];
          goto &Data::Vars::_Var};
      1}';
      eval $proc;
      $@ and die "Fatal error in $pkg\::Vars\::_access_maker?: $@\n";
    }
  } ## end sub _access_maker  }}}
[download]

It didn't like the 'goto'. So... just a bit of uglification:

  sub _access_maker {       #{{{
    my $pkg  = shift;      #var in $_
    {
      my $proc = '# line ' . __LINE__ . ' "' . __FILE__ . "\"\n" . '
      { use warnings;use strict;
        package '.$pkg.'; 
        sub '.$_.' (;$) :lvalue { ' . ($] >= 5.016 ? 
        ' unshift @_, [shift, Data::Vars::varname((caller 0)[3]), want
+array];
          goto &Data::Vars::_Var ' :
        '  &Data::Vars::_Var( 
              [shift, Data::Vars::varname((caller 0)[3]), wantarray], 
+@_); ')
      .'};
      1}';
      eval $proc;
      $@ and die "Fatal error in $pkg\::Vars\::_access_maker?: $@\n";
    }
  } ## end sub _access_maker  }}}
[download]

Ug...Talk about chaotic changes!.... Gonna have to do a bit more testing with this mess of changes...ARG!!!!!!

Thanks!...(I think...*ouch*...)