Interestingly IPv6 removed the checksum from its packet header [1], delegating this work to the higher protocols such as TCP and UDP.[2] So I guess that raises the chance of an invalid IP header getting through. Source and target address will probably result in dropped packets but I wonder what happens if one of the other fields is corrupted, say traffic class.
[1] https://en.wikipedia.org/wiki/IPv6_packet#Fixed_header
[2] https://en.wikipedia.org/wiki/IPv6#Simplified_processing_by_...