Bug 30009: Do not set MARCNOTES to empty list in list context

Bug 30009: Do not set MARCNOTES to empty list in list context

AMENDED:
We should not pass an empty list here, but just undef in order to
prevent creating a shift of elements in the hash.

To test:
1 - Find or create an invalid marc record
2 - View in staff client
3 - Note tab Descriptions(1) has no content
4 - Apply patch, reload
5 - No empty tab

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>