my $Person1 = defined($1) ? $1 : '';
my $Person2 = defined($2) ? $2 : '';

##</code><code>##

if ($Line =~ m/^Pairing Start\s+(\w+)\s+(\w+)/) {

##</code><code>##

Use of uninitialized value within %PairsOf in concatenation (.) or string at ./test_removing_pair_unitialized_value_error.pl line 26, <DATA> line 14.
Use of uninitialized value within %PairsOf in concatenation (.) or string at ./test_removing_pair_unitialized_value_error.pl line 27, <DATA> line 14.
Use of uninitialized value within %PairsOf in concatenation (.) or string at ./test_removing_pair_unitialized_value_error.pl line 27, <DATA> line 14.
Use of uninitialized value within %PairsOf in concatenation (.) or string at ./test_removing_pair_unitialized_value_error.pl line 27, <DATA> line 14.
Use of uninitialized value within %PairsOf in concatenation (.) or string at ./test_removing_pair_unitialized_value_error.pl line 27, <DATA> line 14.