Bug 27626: Fix self registration if categorycode is hidden and PatronSelfRegistrationVerifyByEmail

If categorycode is selected in
PatronSelfRegistrationBorrowerUnwantedField and
PatronSelfRegistrationVerifyByEmail is turned on, the patron self registration
fails with

   [You must provide a patron's category to validate password's strength
   and length] at /usr/share/perl5/Exception/Class/Base.pm line 88

Test plan:
0. Select categorycode in PatronSelfRegistrationBorrowerUnwantedField
   and turn on PatronSelfRegistrationVerifyByEmail
1. Self register a patron
2. Confirm that it works as expected with this patch applied.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>

opac/opac-memberentry.pl

@@ -124,6 +124,7 @@ if ( $action eq 'create' ) {
     my %borrower = ParseCgiForBorrower($cgi);
 
     %borrower = DelEmptyFields(%borrower);
+    $borrower{categorycode} ||= C4::Context->preference('PatronSelfRegistrationDefaultCategory');
 
     my @empty_mandatory_fields = (CheckMandatoryFields( \%borrower, $action ), CheckMandatoryAttributes( \%borrower, $attributes ) );
     my $invalidformfields = CheckForInvalidFields(\%borrower);
@@ -219,7 +220,6 @@ if ( $action eq 'create' ) {
                 }
             );
 
-            $borrower{categorycode}     ||= C4::Context->preference('PatronSelfRegistrationDefaultCategory');
             $borrower{password}         ||= Koha::AuthUtils::generate_password(Koha::Patron::Categories->find($borrower{categorycode}));
             my $consent_dt = delete $borrower{gdpr_proc_consent};
             my $patron = Koha::Patron->new( \%borrower )->store;