Fix / no pool code 500 error on balancer

src/routes/balancer.route.js

@@ -84,9 +84,8 @@ router.post('/sell-price', async (req, res) => {
       maxSwaps,
     )
 
-    const gasLimit = estimateGasLimit(swaps.length)
-
     if (swaps != null && expectedOut != null) {
+      const gasLimit = estimateGasLimit(swaps.length)
       res.status(200).json({
         network: balancer.network,
         timestamp: initTime,
@@ -145,9 +144,8 @@ router.post('/buy-price', async (req, res) => {
       maxSwaps,
     )
 
-    const gasLimit = estimateGasLimit(swaps.length)
-
     if (swaps != null && expectedIn != null) {
+      const gasLimit = estimateGasLimit(swaps.length)
       res.status(200).json({
         network: balancer.network,
         timestamp: initTime,

src/services/eth.js

@@ -65,15 +65,17 @@ export default class Ethereum {
   }
 
   // approve a spender to transfer tokens from a wallet address
-  async approveERC20 (wallet, spender, tokenAddress, amount, gasPrice = this.gasPrice, gasLimit = 50000) {
+  async approveERC20 (wallet, spender, tokenAddress, amount, gasPrice = this.gasPrice, gasLimit) {
     try {
+      // fixate gas limit to prevent overwriting
+      const approvalGasLimit = 50000
       // instantiate a contract and pass in wallet, which act on behalf of that signer
       const contract = new ethers.Contract(tokenAddress, abi.ERC20Abi, wallet)
       return await contract.approve(
         spender,
         amount, {
           gasPrice: gasPrice * 1e9,
-          gasLimit: gasLimit
+          gasLimit: approvalGasLimit
         }
       )
     } catch (err) {