33_readingsGroup.pm: fixed some warnings

git-svn-id: https://svn.fhem.de/fhem/trunk@14033 2b470e98-0d58-463d-a4d8-8e2adae1ed80

fhem/FHEM/33_readingsGroup.pm

@@ -257,6 +257,8 @@ rgVal2Num($)
 {
   my ($val) = @_;
 
+  return $val if( !defined($val) );
+
   #$val =~ s/[^-\.\d]//g if( defined($val) );
   $val = ($val =~ /(-?\d+(\.\d+)?)/ ? $1 : "");
 
@@ -1381,8 +1383,6 @@ readingsGroup_Notify($$)
 
           my $value_style = lookup2($hash->{helper}{valueStyle},$n,$reading,$value);
 
-          my $value = $value;
-
           my $value_orig = $value;
           if( my $value_format = $hash->{helper}{valueFormat} ) {
             my $value_format = lookup2($hash->{helper}{valueFormat},$n,$reading,$value);