Bug 37742: Fix error display

Bug 37742: Fix error display

This change fixes the display of the error message on "My virtual card"
on the OPAC.

Test plan:
0. Apply the patch and enable syspref "OPACVirtualCard"
1. Go to http://localhost:8081/cgi-bin/koha/members/memberentry.pl
?op=edit_form&destination=circ&borrowernumber=51
2. Add an asterisk (*) to the end of the card number
3. Go to http://localhost:8080/cgi-bin/koha/opac-virtual-card.pl
4. Note that the error message appears as follows:
Code 39 must contain only digits, capital letters, spaces and the symbols -.$/+%

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>