SoftEtherVPN Affected by NULL dereference in DeleteIPv6DefaultRouterInRA

SoftEtherVPN is a an open-source cross-platform multi-protocol VPN Program. Versions 5.02.5184 to 5.02.5187 are vulnerable to NULL dereference in `DeleteIPv6DefaultRouterInRA` called by `StorePacket`. Before dereferencing, `DeleteIPv6DefaultRouterInRA` does not account for `ParsePacket` returning NULL, resulting in the program crashing. A patched version does not exist at this time.