while (<DATA>) {
   die "Error!" if $_ eq ".\n";
}

__DATA__
a
b
c
.
d
e

##</code><code>##

Error! at script.pl line 2, <DATA> line 4.

##</code><code>##

<DATA>;
die "Error!";

__DATA__
a
b

##</code><code>##

Error! at script.pl line 2, <DATA> line 1.

##</code><code>##

<DATA>;
close(DATA);
die "Error!";

__DATA__
a
b

##</code><code>##

Error! at script.pl line 3.

##</code><code>##

<DATA>;
$. = 100;
die "Error!";

__DATA__
a
b

##</code><code>##

Error! at script.pl line 3, <DATA> line 100.

##</code><code>##

<DATA>;
$. = 0;
die "Error!";

__DATA__
a
b

##</code><code>##

Error! at script.pl line 3.

##</code><code>##

Error! at script.pl line 3, filename.dat line 100.