refactor(x/group): check the new admin address when updating the group policy admin (backport #18350) (#18352)

Co-authored-by: Luke Ma <lukema95@gmail.com>

x/group/keeper/msg_server.go

@@ -429,6 +429,10 @@ func (k Keeper) UpdateGroupPolicyAdmin(goCtx context.Context, msg *group.MsgUpda
 		return nil, errorsmod.Wrap(errors.ErrInvalid, "new and old admin are same")
 	}
 
+	if _, err := k.accKeeper.AddressCodec().StringToBytes(msg.NewAdmin); err != nil {
+		return nil, errorsmod.Wrap(sdkerrors.ErrInvalidAddress, "new admin address")
+	}
+
 	ctx := sdk.UnwrapSDKContext(goCtx)
 	action := func(groupPolicy *group.GroupPolicyInfo) error {
 		groupPolicy.Admin = msg.NewAdmin

x/group/keeper/msg_server_test.go

@@ -661,6 +661,15 @@ func (s *TestSuite) TestUpdateGroupAdmin() {
 				CreatedAt:   s.blockTime,
 			},
 		},
+		"with invalid new admin address": {
+			req: &group.MsgUpdateGroupAdmin{
+				GroupId:  groupID,
+				Admin:    oldAdmin,
+				NewAdmin: "%s",
+			},
+			expErr:    true,
+			expErrMsg: "new admin address",
+		},
 	}
 	for msg, spec := range specs {
 		spec := spec
@@ -1215,6 +1224,23 @@ func (s *TestSuite) TestUpdateGroupPolicyAdmin() {
 			},
 			expErr: false,
 		},
+		"with invalid new admin address": {
+			req: &group.MsgUpdateGroupPolicyAdmin{
+				Admin:              admin.String(),
+				GroupPolicyAddress: groupPolicyAddr,
+				NewAdmin:           "%s",
+			},
+			expGroupPolicy: &group.GroupPolicyInfo{
+				Admin:          admin.String(),
+				Address:        groupPolicyAddr,
+				GroupId:        myGroupID,
+				Version:        2,
+				DecisionPolicy: nil,
+				CreatedAt:      s.blockTime,
+			},
+			expErr:    true,
+			expErrMsg: "new admin address",
+		},
 	}
 	for msg, spec := range specs {
 		spec := spec