prev base fee per gas avoids returning nil to avoid method handler cr…

…ashed on replay

x/evm/keeper/fee.go

@@ -11,14 +11,11 @@ func (k *Keeper) AdjustDynamicBaseFeePerGas(ctx sdk.Context, blockGasUsed uint64
 		return nil
 	}
 	prevBaseFee := k.GetPrevBlockBaseFeePerGas(ctx)
-	if prevBaseFee.IsNil() {
-		prevBaseFee = types.DefaultParams().MinimumFeePerGas
-	}
 	// set the resulting base fee for block n-1 on block n
 	k.SetDynamicBaseFeePerGas(ctx, prevBaseFee)
 	targetGasUsed := sdk.NewDec(int64(k.GetTargetGasUsedPerBlock(ctx)))
-	if targetGasUsed.IsZero() {
-		return &prevBaseFee
+	if targetGasUsed.IsZero() { // avoid division by zero
+		return &prevBaseFee // return the previous base fee as is
 	}
 	minimumFeePerGas := k.GetParams(ctx).MinimumFeePerGas
 	maximumFeePerGas := k.GetParams(ctx).MaximumFeePerGas
@@ -104,7 +101,11 @@ func (k *Keeper) GetPrevBlockBaseFeePerGas(ctx sdk.Context) sdk.Dec {
 	store := ctx.KVStore(k.storeKey)
 	bz := store.Get(types.PrevBlockBaseFeePerGasPrefix)
 	if bz == nil {
-		return sdk.Dec{}
+		minFeePerGas := k.GetMinimumFeePerGas(ctx)
+		if minFeePerGas.IsNil() {
+			minFeePerGas = types.DefaultParams().MinimumFeePerGas
+		}
+		return minFeePerGas
 	}
 	d := sdk.Dec{}
 	err := d.UnmarshalJSON(bz)

x/evm/keeper/fee_test.go

@@ -202,3 +202,16 @@ func TestGetDynamicBaseFeePerGasWithNilMinFee(t *testing.T) {
 	require.Equal(t, expectedFee, fee)
 	require.False(t, fee.IsNil())
 }
+
+func TestGetPrevBlockBaseFeePerGasWithNilMinFee(t *testing.T) {
+	k, ctx := testkeeper.MockEVMKeeper()
+
+	// Test case 1: When dynamic base fee doesn't exist and minimum fee is nil
+	store := ctx.KVStore(k.GetStoreKey())
+	store.Delete(types.BaseFeePerGasPrefix)
+
+	// Clear the dynamic base fee from store
+	fee := k.GetDynamicBaseFeePerGas(ctx)
+	require.Equal(t, types.DefaultParams().MinimumFeePerGas, fee)
+	require.False(t, fee.IsNil())
+}