refactor: panic on ZeroCustomFields for solo machine implementation (#…

…1972)

* refactor: panic on ZeroCustomFields for solo machine implementation

* chore: changelog

CHANGELOG.md

@@ -111,6 +111,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (modules/core/02-client) [\#1741](https://github.com/cosmos/ibc-go/pull/1741) Emitting a new `upgrade_chain` event upon setting upgrade consensus state.
 * (client) [\#724](https://github.com/cosmos/ibc-go/pull/724) `IsRevisionFormat` and `IsClientIDFormat` have been updated to disallow newlines before the dash used to separate the chainID and revision number, and the client type and client sequence.
 * (02-client/cli) [\#897](https://github.com/cosmos/ibc-go/pull/897) Remove `GetClientID()` from `Misbehaviour` interface. Submit client misbehaviour cli command requires an explicit client id now.
+* (06-solomachine) [\#1972](https://github.com/cosmos/ibc-go/pull/1972) Solo machine implementation of `ZeroCustomFields` fn now panics as the fn is only used for upgrades which solo machine does not support. 
 
 ### Features
 

modules/light-clients/06-solomachine/client_state.go

@@ -75,11 +75,9 @@ func (cs ClientState) Validate() error {
 	return cs.ConsensusState.ValidateBasic()
 }
 
-// ZeroCustomFields returns solomachine client state with client-specific field FrozenSequence zeroed out
+// ZeroCustomFields is not implemented for solo machine
 func (cs ClientState) ZeroCustomFields() exported.ClientState {
-	return NewClientState(
-		cs.Sequence, cs.ConsensusState,
-	)
+	panic("ZeroCustomFields is not implemented as the solo machine implementation does not support upgrades.")
 }
 
 // Initialize will check that initial consensus state is equal to the latest consensus state of the initial client.