util/dofile.pl: report if a template couldn't be loaded

my $prev_linecount = 0;

my $text =

    @ARGV

    ? join("", map { my $x = "{- output_reset_on() -}".Text::Template::_load_text($_);

    ? join("", map { my $x = Text::Template::_load_text($_);

                     if (!defined($x)) {

                         die $Text::Template::ERROR, "\n";

                     }

                     $x = "{- output_reset_on() -}" . $x;

                     my $linecount = $x =~ tr/\n//;

                     $prev_linecount = ($linecount += $prev_linecount);

                     $lines{$linecount} = $_;