Fix problem found in dlc@4b9bd10#commitcomment-1540416.

MANIFEST

@@ -24,5 +24,6 @@ t/13.t
 t/14.t
 t/15.t
 t/16.t
+t/17.t
 TabularDisplay.pm
 META.yml                                 Module meta-data (added by MakeMaker)

README

@@ -235,5 +235,5 @@ CREDITS
         Patrick Kuijvenhoven
 
 VERSION
-    This documentation describes "Text::TabularDisplay" version 1.32.
+    This documentation describes "Text::TabularDisplay" version 1.33.
 

TabularDisplay.pm

@@ -23,7 +23,7 @@ use strict;
 use integer;
 use vars qw($VERSION);
 
-$VERSION = "1.32";
+$VERSION = "1.33";
 
 # ---======================= Public Methods ======================---
 
@@ -251,7 +251,7 @@ sub _format_line {
     my $height = 0;
     my @col_lines;
     for (@$columns) {
-        my @lines = split "\n", (defined $_ ? $_ : '');
+        my @lines = split "\n", ((defined $_ && length $_) ? $_ : ' ');
         $height = scalar @lines
             if $height < @lines;
         push @col_lines, \@lines;
@@ -556,5 +556,5 @@ feedback, or good karma:
 
 =head1 VERSION
 
-This documentation describes C<Text::TabularDisplay> version 1.32.
+This documentation describes C<Text::TabularDisplay> version 1.33.
 

t/17.t

@@ -0,0 +1,34 @@
+#!/usr/bin/perl
+# vim: set ft=perl:
+# Test suggested by Patrick Kuijvenhoven <https://github.com/petski>
+# in https://github.com/dlc/text--tabulardisplay/commit/4b9bd105d9ebaf8ac838e8e993216e4b56d85683#commitcomment-1540416
+
+use strict;
+use Text::TabularDisplay;
+use Test;
+
+BEGIN {
+    plan tests => 1;
+}
+
+my @data = (
+    ["a", "b"],
+    ["", ""],
+    [undef, ""],
+    ["", undef],
+    [undef, undef],
+    [0, 0],
+);
+
+my $t = Text::TabularDisplay->new("a", "b");
+$t->populate([ @data ]);
+ok($t->render, "+---+---+
+| a | b |
++---+---+
+| a | b |
+|   |   |
+|   |   |
+|   |   |
+|   |   |
+| 0 | 0 |
++---+---+");