fix: gas estimate error

fixes #935
A bug occurs when someone requests a large amount of funds from you since the gas estimation will fail and there isn't a way of handling errors in the source yet.

This PR handles the error appropriatley for both `estimateGas` and `estimateTokenGas` where the response is only converted from hex to int if the RPC call was successful. Otherwise return the error message as the response and let the UI decide how to display it.

Currently the error for gas estimation in transaction bubbles is displayed in a popup however, ive come to realize that 2 popups open instead of one. This is a new bug of which I can't pinpoint the root cause at the moment and have opted to file a separate issue for it.

src/app/wallet/view.nim

@@ -273,13 +273,18 @@ QtObject:
   
   proc estimateGas*(self: WalletView, from_addr: string, to: string, assetAddress: string, value: string, data: string = ""): string {.slot.} =
     var
-      response: int
+      response: string
       success: bool
     if assetAddress != ZERO_ADDRESS and not assetAddress.isEmptyOrWhitespace:
       response = self.status.wallet.estimateTokenGas(from_addr, to, assetAddress, value, success)
     else:
       response = self.status.wallet.estimateGas(from_addr, to, value, data, success)
-    result = $(%* { "result": %response, "success": %success })
+
+    if success == true:
+      let res = fromHex[int](response)
+      result = $(%* { "result": %res, "success": %success })
+    else:
+      result = $(%* { "result": "-1", "success": %success, "error": { "message": %response } })
 
   proc transactionWasSent*(self: WalletView, txResult: string) {.signal.}
 

src/status/wallet.nim

@@ -72,15 +72,14 @@ proc buildTokenTransaction(self: WalletModel, source, to, assetAddress: Address,
 proc getKnownTokenContract*(self: WalletModel, address: Address): Erc20Contract =
   getErc20Contracts().concat(getCustomTokens()).getErc20ContractByAddress(address)
 
-proc estimateGas*(self: WalletModel, source, to, value, data: string, success: var bool): int =
+proc estimateGas*(self: WalletModel, source, to, value, data: string, success: var bool): string =
   var tx = transactions.buildTransaction(
     parseAddress(source),
     eth2Wei(parseFloat(value), 18),
     data = data
   )
   tx.to = parseAddress(to).some
-  let response = eth.estimateGas(tx, success)
+  result = eth.estimateGas(tx, success)
-  result = fromHex[int](response)
 
 proc getTransactionReceipt*(self: WalletModel, transactionHash: string): JsonNode =
   result = status_wallet.getTransactionReceipt(transactionHash).parseJSON()["result"]
@@ -110,7 +109,7 @@ proc checkPendingTransactions*(self: WalletModel) =
 proc checkPendingTransactions*(self: WalletModel, address: string, blockNumber: int) =
   self.confirmTransactionStatus(status_wallet.getPendingOutboundTransactionsByAddress(address).parseJson["result"], blockNumber)
   
-proc estimateTokenGas*(self: WalletModel, source, to, assetAddress, value: string, success: var bool): int =
+proc estimateTokenGas*(self: WalletModel, source, to, assetAddress, value: string, success: var bool): string =
   var
     transfer: Transfer
     contract: Erc20Contract
@@ -123,8 +122,7 @@ proc estimateTokenGas*(self: WalletModel, source, to, assetAddress, value: strin
       contract
     )
 
-  let response = contract.methods["transfer"].estimateGas(tx, transfer, success)
+  result = contract.methods["transfer"].estimateGas(tx, transfer, success)
-  result = fromHex[int](response)
 
 proc sendTransaction*(self: WalletModel, source, to, value, gas, gasPrice, password: string, success: var bool, data = ""): string =
   var tx = transactions.buildTransaction(

ui/app/AppLayouts/Chat/ChatColumn/ChatComponents/SignTransactionModal.qml

@@ -31,10 +31,6 @@ ModalPopup {
         root.close()
     }
 
-    function estimateGas(){
-        gasSelector.estimateGas()
-    }
-
     id: root
 
     //% "Send"
@@ -139,7 +135,10 @@ ModalPopup {
 
                     if (!gasEstimate.success) {
                         //% "Error estimating gas: %1"
-                        console.warn(qsTrId("error-estimating-gas---1").arg(gasEstimate.error.message))
+                        let message = qsTrId("error-estimating-gas---1").arg(gasEstimate.error.message)
+                        console.warn(message)
+                        gasEstimateErrorPopup.confirmationText = message + qsTr(". The transaction will probably fail.")
+                        gasEstimateErrorPopup.open()
                         return
                     }
                     selectedGasLimit = gasEstimate.result

ui/app/AppLayouts/Chat/ChatColumn/MessageComponents/TransactionComponents/AcceptTransaction.qml

@@ -77,6 +77,14 @@ Item {
         }
     }
 
+    ConfirmationDialog {
+        id: gasEstimateErrorPopup
+        height: 220
+        onConfirmButtonClicked: {
+            gasEstimateErrorPopup.close();
+        }
+    }
+
     Loader {
         id: signTransactionModal
         function open() {