57_CALVIEW.pm: -changed the way to test values, thx klausw

git-svn-id: https://svn.fhem.de/fhem/trunk@11819 2b470e98-0d58-463d-a4d8-8e2adae1ed80

fhem/FHEM/57_CALVIEW.pm

@@ -100,7 +100,7 @@ sub CALVIEW_GetUpdate($){
 		my @bts=str2time($M."/".$D."/".$Y." ".$tempstart[1]);
 		#replace the "\," with ","
 		if(length($item->[1]) > 0){ $item->[1] =~ s/\\,/,/g; }
-		if(length($item->[4]) > 0){ $item->[4] =~ s/\\,/,/g; }
+		if( defined($item->[4]) && length($item->[4]) > 0){ $item->[4] =~ s/\\,/,/g; }
 		push @termineNew,{
 			bdate => $tempstart[0],
 			btime => $tempstart[1],