use 5.010; 
my $is_dev_mode = $param->{is_dev_mode} // 1;

##</code><code>##

my $is_dev_mode = defined $param->{is_dev_mode} ? $param->{is_dev_mode} : 1;

##</code><code>##

#  it would likely help your future self to add a comment here if you do this
my $is_dev_mode = !!$param->{is_dev_mode} || 0;