make try-block smaller

waku/incentivization/txid_proof.nim

@@ -18,33 +18,35 @@ proc isEligibleTxId*(
     return err("Eligibility proof is empty")
   let txHash = TxHash.fromHex(byteutils.toHex(eligibilityProof.proofOfPayment.get()))
   let web3 = await newWeb3(ethClient)
+  var tx: TransactionObject
+  var txReceipt: ReceiptObject
   try:
     # TODO: make requests in parallel (?)
-    let tx = await web3.provider.eth_getTransactionByHash(txHash)
-    let txReceipt = await web3.getMinedTransactionReceipt(txHash)
-    # check that it is not a contract creation tx
-    let toAddressOption = txReceipt.to
-    if toAddressOption.isNone:
-      # this is a contract creation tx
-      return err("A contract creation tx is not eligible")
-    # check that it is a simple transfer (not a contract call)
-    # a simple transfer uses 21000 gas
-    let gasUsed = txReceipt.gasUsed
-    let isSimpleTransferTx = (gasUsed == SimpleTransferGasUsed)
-    if not isSimpleTransferTx:
-      return err("A contract call tx is not eligible")
-    # check that the to address is "as expected"
-    let toAddress = toAddressOption.get()
-    if toAddress != expectedToAddress:
-      return err("Wrong destination address: " & $toAddress)
-    # check that the amount is "as expected"
-    let txValue = tx.value
-    if txValue != expectedValue:
-      return err("Wrong tx value: got " & $txValue & ", expected " & $expectedValue)
-    defer:
-      await web3.close()
-    return ok()
+    tx = await web3.provider.eth_getTransactionByHash(txHash)
+    txReceipt = await web3.getMinedTransactionReceipt(txHash)
   except ValueError:
     let errorMsg = "Failed to fetch tx or tx receipt: " & getCurrentExceptionMsg()
     error "exception in isEligibleTxId", error = $errorMsg
     return err($errorMsg)
+  # check that it is not a contract creation tx
+  let toAddressOption = txReceipt.to
+  if toAddressOption.isNone:
+    # this is a contract creation tx
+    return err("A contract creation tx is not eligible")
+  # check that it is a simple transfer (not a contract call)
+  # a simple transfer uses 21000 gas
+  let gasUsed = txReceipt.gasUsed
+  let isSimpleTransferTx = (gasUsed == SimpleTransferGasUsed)
+  if not isSimpleTransferTx:
+    return err("A contract call tx is not eligible")
+  # check that the to address is "as expected"
+  let toAddress = toAddressOption.get()
+  if toAddress != expectedToAddress:
+    return err("Wrong destination address: " & $toAddress)
+  # check that the amount is "as expected"
+  let txValue = tx.value
+  if txValue != expectedValue:
+    return err("Wrong tx value: got " & $txValue & ", expected " & $expectedValue)
+  defer:
+    await web3.close()
+  return ok()