Don't crash for zero liquidity pairs

src/entities/trade.ts

@@ -166,6 +166,7 @@ export class Trade {
       const pair = pairs[i]
       // pair irrelevant
       if (!pair.token0.equals(amountIn.token) && !pair.token1.equals(amountIn.token)) continue
+      if (pair.reserve0.equalTo(ZERO) || pair.reserve1.equalTo(ZERO)) continue
 
       let amountOut: TokenAmount
       try {
@@ -234,6 +235,7 @@ export class Trade {
       const pair = pairs[i]
       // pair irrelevant
       if (!pair.token0.equals(amountOut.token) && !pair.token1.equals(amountOut.token)) continue
+      if (pair.reserve0.equalTo(ZERO) || pair.reserve1.equalTo(ZERO)) continue
 
       let amountIn: TokenAmount
       try {

test/trade.test.ts

@@ -13,6 +13,8 @@ describe('Trade', () => {
   const pair_1_2 = new Pair(new TokenAmount(token1, JSBI.BigInt(1200)), new TokenAmount(token2, JSBI.BigInt(1000)))
   const pair_1_3 = new Pair(new TokenAmount(token1, JSBI.BigInt(1200)), new TokenAmount(token3, JSBI.BigInt(1300)))
 
+  const empty_pair_0_1 = new Pair(new TokenAmount(token0, JSBI.BigInt(0)), new TokenAmount(token1, JSBI.BigInt(0)))
+
   describe('#bestTradeExactIn', () => {
     it('throws with empty pairs', () => {
       expect(() => Trade.bestTradeExactIn([], new TokenAmount(token0, JSBI.BigInt(100)), token2)).toThrow('PAIRS')
@@ -40,6 +42,12 @@ describe('Trade', () => {
       expect(result[1].outputAmount).toEqual(new TokenAmount(token2, JSBI.BigInt(69)))
     })
 
+    it('doesnt throw for zero liquidity pairs', () => {
+      expect(Trade.bestTradeExactIn([empty_pair_0_1], new TokenAmount(token0, JSBI.BigInt(100)), token1)).toHaveLength(
+        0
+      )
+    })
+
     it('respects maxHops', () => {
       const result = Trade.bestTradeExactIn(
         [pair_0_1, pair_0_2, pair_1_2],
@@ -224,6 +232,12 @@ describe('Trade', () => {
       expect(result[1].outputAmount).toEqual(new TokenAmount(token2, JSBI.BigInt(100)))
     })
 
+    it('doesnt throw for zero liquidity pairs', () => {
+      expect(Trade.bestTradeExactOut([empty_pair_0_1], token1, new TokenAmount(token1, JSBI.BigInt(100)))).toHaveLength(
+        0
+      )
+    })
+
     it('respects maxHops', () => {
       const result = Trade.bestTradeExactOut(
         [pair_0_1, pair_0_2, pair_1_2],