fix: err check (cosmos#1880)

* fix: change log.Fatal to panic, defer iter.Close()

* update export.go

* fix: lint

app/export.go

@@ -2,7 +2,6 @@ package gaia
 
 import (
 	"encoding/json"
-	"log"
 
 	servertypes "github.com/cosmos/cosmos-sdk/server/types"
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -59,7 +58,7 @@ func (app *GaiaApp) prepForZeroHeightGenesis(ctx sdk.Context, jailAllowedAddrs [
 	for _, addr := range jailAllowedAddrs {
 		_, err := sdk.ValAddressFromBech32(addr)
 		if err != nil {
-			log.Fatal(err)
+			panic(err)
 		}
 		allowedAddrsMap[addr] = true
 	}
@@ -110,7 +109,7 @@ func (app *GaiaApp) prepForZeroHeightGenesis(ctx sdk.Context, jailAllowedAddrs [
 
 		err := app.DistrKeeper.Hooks().AfterValidatorCreated(ctx, val.GetOperator())
 		if err != nil {
-			log.Fatal(err)
+			panic(err)
 		}
 		return false
 	})
@@ -163,6 +162,7 @@ func (app *GaiaApp) prepForZeroHeightGenesis(ctx sdk.Context, jailAllowedAddrs [
 	// update bond intra-tx counters.
 	store := ctx.KVStore(app.GetKey(stakingtypes.StoreKey))
 	iter := sdk.KVStoreReversePrefixIterator(store, stakingtypes.ValidatorsKey)
+
 	counter := int16(0)
 
 	for ; iter.Valid(); iter.Next() {
@@ -185,7 +185,7 @@ func (app *GaiaApp) prepForZeroHeightGenesis(ctx sdk.Context, jailAllowedAddrs [
 
 	_, err := app.StakingKeeper.ApplyAndReturnValidatorSetUpdates(ctx)
 	if err != nil {
-		log.Fatal(err)
+		panic(err)
 	}
 
 	/* Handle slashing state. */