NewDecFromCoins can make nil item in the result DecCoins

[yun-yeo]

Summary of Bug

cosmos-sdk/types/dec_coin.go

Lines 184 to 190 in daca54d

	func NewDecCoinsFromCoins(coins ...Coin) DecCoins {
	decCoins := make(DecCoins, len(coins))
	newCoins := NewCoins(coins...)
	for i, coin := range newCoins {
	decCoins[i] = NewDecCoinFromCoin(coin)
	}

The problem is happending when there is zero coin in the input coins array.

In function NewDecFromCoins, it create DecCoin array first and later fill the array. However the function NewCoins(coins...) can return shorten array rather than a same length of coins array because it removes zero coins from the array. This shorten result array causes the result DecCoins array to have nil item.

Ex)

input coins: 
[ {denom: "uatom", amount: 0}, {denom: "utest", amount: 100}]

result of NewCoins: 
[{denom: "utest", amount: 100}]

result of NewDecFromCoins : 
[{denom: "utest", amount: 100.0}, nil]

Version

all versions

Steps to Reproduce

Call NewDecFromCoins function with coins array which contains zero coin.