Add some null checking -- if the string is undefined, then turn it into the empty string. This avoids many undefined value warnings when the data provided by the user is incomplete.

webtools/PLIF/PLIF/Input/CGI.pm

@@ -73,6 +73,7 @@ sub splitArguments {
                 my $value = $2;
                 # decode the strings
                 foreach my $string ($name, $value) {
+                    if (defined($string)) {
                         $string =~ tr/+/ /; # convert + to spaces
                         $string =~ s/% # a percent symbol
                                      ( # followed by
@@ -80,6 +81,9 @@ sub splitArguments {
                                      ) # which we shall put in $1
                          /chr(hex($1)) # and convert back into a character
                                 /egox; # (evaluate, globally, optimised, with comments)
+                    } else {
+                        $string = '';
+                    }
                 }
                 $self->addArgument($name, $value);
             } else {