This avoids thousands of "uninitialized value" warnings

Martin Kaistra authored Aug 08, 2021 and derf committed Aug 08, 2021

Signed-off-by: Martin Kaistra <admin@djfun.de>

served by a cross-country S-Bahn line

via <https://github.com/marudor/BahnhofsAbfahrten/issues/499>

This fixes transfer trains getting lost when requested from a related station

Notable offender: "Berlin Südkreuz" lacked S 41 / S42 (ring line
from Südkreuz (S) to Südkreuz (S) with transfer to/from the next/previous
incarnation), as it referenced "Berlin Südkreuz (S)". "Berlin Südkreuz (S)"
itself worked fine.