[R4R] address potential panic in validator vesting (#645)

* emit event instead of panic on undelegation errors

x/validator-vesting/keeper/keeper.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/cosmos/cosmos-sdk/codec"
 	sdk "github.com/cosmos/cosmos-sdk/types"
+	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
 	stakingexported "github.com/cosmos/cosmos-sdk/x/staking/exported"
 
 	"github.com/tendermint/tendermint/libs/log"
@@ -185,7 +186,13 @@ func (k Keeper) HandleVestingDebt(ctx sdk.Context, addr sdk.AccAddress, blockTim
 		k.stakingKeeper.IterateDelegations(ctx, vv.Address, func(index int64, d stakingexported.DelegationI) (stop bool) {
 			_, err := k.stakingKeeper.Undelegate(ctx, d.GetDelegatorAddr(), d.GetValidatorAddr(), d.GetShares())
 			if err != nil {
-				panic(err)
+				ctx.EventManager().EmitEvent(
+					sdk.NewEvent(
+						types.EventTypeBeginBlockError,
+						sdk.NewAttribute(sdk.AttributeKeyModule, types.AttributeValueCategory),
+						sdk.NewAttribute(types.AttributeKeyError, fmt.Sprintf("%s", sdkerrors.Wrapf(types.ErrFailedUndelegation, "%s", err.Error()))),
+					),
+				)
 			}
 			return false
 		})

x/validator-vesting/types/errors.go

@@ -0,0 +1,12 @@
+package types
+
+import (
+	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
+)
+
+// DONTCOVER
+
+var (
+	// ErrFailedUndelegation error for delegations that fail to unbond
+	ErrFailedUndelegation = sdkerrors.Register(ModuleName, 2, "undelegation failed")
+)

x/validator-vesting/types/events.go

@@ -0,0 +1,9 @@
+package types
+
+// Event types for validator vesting module
+const (
+	EventTypeBeginBlockError = "begin_blocker_error"
+
+	AttributeValueCategory = "validator-vesting"
+	AttributeKeyError      = "error_message"
+)