feat(client/v2): improve error message on enums (#21936)

client/v2/CHANGELOG.md

@@ -43,6 +43,10 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * [#18626](https://github.com/cosmos/cosmos-sdk/pull/18626) Support for off-chain signing and verification of a file.
 * [#18461](https://github.com/cosmos/cosmos-sdk/pull/18461) Support governance proposals.
 
+### Improvements
+
+* [#21936](https://github.com/cosmos/cosmos-sdk/pull/21936) Print possible enum values in error message after an invalid input was provided.
+
 ### API Breaking Changes
 
 * [#17709](https://github.com/cosmos/cosmos-sdk/pull/17709) Address codecs have been removed from `autocli.AppOptions` and `flag.Builder`. Instead client/v2 uses the address codecs present in the context (introduced in [#17503](https://github.com/cosmos/cosmos-sdk/pull/17503)).

client/v2/autocli/flag/enum.go

@@ -58,7 +58,12 @@ func (e enumValue) String() string {
 func (e *enumValue) Set(s string) error {
 	valDesc, ok := e.valMap[s]
 	if !ok {
-		return fmt.Errorf("%s is not a valid value for enum %s", s, e.enum.FullName())
+		var validValues []string
+		for k := range e.valMap {
+			validValues = append(validValues, k)
+		}
+
+		return fmt.Errorf("%s is not a valid value for enum %s. Valid values are: %s", s, e.enum.FullName(), strings.Join(validValues, ", "))
 	}
 	e.value = valDesc.Number()
 	return nil