``` panic: runtime error: invalid memory address or nil pointer dereference [signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x77c8a9] goroutine 99 [running]: github.com/blinklabs-io/gouroboros/ledger/conway.(*ConwayTransactionBody).ProtocolParameterUpdates(...) /gomod-cache/github.com/blinklabs-io/gouroboros@v0.128.0/ledger/conway/conway.go:406 github.com/blinklabs-io/gouroboros/ledger/conway.ConwayTransaction.ProtocolParameterUpdates(...) /gomod-cache/github.com/blinklabs-io/gouroboros@v0.128.0/ledger/conway/conway.go:539 ```