Do not print error when encountering an empty database

sub get_schema_version {

	my ($dbh) = @_;

	my $schema_version

	  = $dbh->selectall_arrayref(qq{select version from schema_version});

	if ( not defined $schema_version ) {

	# We do not want DBD to print an SQL error if schema_version does not

	# exist, as this is not an error in this case. Setting $dbh->{PrintError} =

	# 0 would disable error printing for all subsequent SQL operations, however,

	# we only want to disable it for this specific query. Hence we use a

	# prepared statement and only disable error printing only there.

	my $sth = $dbh->prepare(qq{select version from schema_version});

	$sth->{PrintError} = 0;

	my $success = $sth->execute;

	if ( not defined $success ) {

		return undef;

	}

	elsif ( @{$schema_version} == 1 ) {

		return $schema_version->[0][0];

	my $rows = $sth->fetchall_arrayref;

	if ( @{$rows} == 1 ) {

		return $rows->[0][0];

	}

	else {

		printf( "Found multiple schema versions: %s", @{$schema_version} );

		printf( "Found multiple schema versions: %s", @{$rows} );

		exit(1);

	}

}