die if we don't get data (usb unplug)

diff --git a/pms3003.pl b/pms3003.pl
index 2d52db8..4cb8b14 100755 (executable)
--- a/pms3003.pl
+++ b/pms3003.pl
@@ -36,6 +36,7 @@ pm10_r
 while (1) {
 
        my ($len, $string) = $s->read(24);
 while (1) {
 
        my ($len, $string) = $s->read(24);

+       die $! if ! defined($len);

        if ( $len > 0 ) {
                my @v = unpack('n*', $string);
                warn "# $len ",dump($string), dump( @v ), $/ if $debug;
        if ( $len > 0 ) {
                my @v = unpack('n*', $string);
                warn "# $len ",dump($string), dump( @v ), $/ if $debug;