add custom error

libs/remix-lib/src/execution/txExecution.ts

 'use strict'
 import { ethers } from 'ethers'
+import { getFunctionFragment } from './txHelper'
 
 /**
   * deploy the given contract
@@ -56,7 +57,7 @@ export function callFunction (from, to, data, value, gasLimit, funAbi, txRunner,
   * @param {Object} execResult    - execution result given by the VM
   * @return {Object} -  { error: true/false, message: DOMNode }
   */
-export function checkVMError (execResult) {
+export function checkVMError (txResult, abi) {
   const errorCode = {
     OUT_OF_GAS: 'out of gas',
     STACK_UNDERFLOW: 'stack underflow',
@@ -74,10 +75,10 @@ export function checkVMError (execResult) {
     error: false,
     message: ''
   }
-  if (!execResult.exceptionError) {
+  if (!txResult.result.execResult.exceptionError) {
     return ret
   }
-  const exceptionError = execResult.exceptionError.error || ''
+  const exceptionError = txResult.result.execResult.exceptionError.error || ''
   const error = `VM error: ${exceptionError}.\n`
   let msg
   if (exceptionError === errorCode.INVALID_OPCODE) {
@@ -87,20 +88,49 @@ export function checkVMError (execResult) {
     msg = '\tThe transaction ran out of gas. Please increase the Gas Limit.\n'
     ret.error = true
   } else if (exceptionError === errorCode.REVERT) {
-    const returnData = execResult.returnValue
+    const returnData = txResult.result.execResult.returnValue
+    const returnDataHex = returnData.slice(0, 4).toString('hex')
+    let customError
+    if (abi) {      
+      let decodedCustomErrorInputs
+      for (const item of abi) {
+        if (item.type === 'error') {
+          // ethers doesn't crash anymore if "error" type is specified, but it doesn't extract the errors. see:
+          // https://github.com/ethers-io/ethers.js/commit/bd05aed070ac9e1421a3e2bff2ceea150bedf9b7
+          // we need here to fake the type, so the "getSighash" function works properly
+          const fn = getFunctionFragment({ ...item, type: 'function', stateMutability: "nonpayable" })
+          if (!fn) continue
+          const sign = fn.getSighash(item.name)
+          if (!sign) continue
+          if (returnDataHex === sign.replace('0x', '')) {
+            customError = item.name
+            decodedCustomErrorInputs = fn.decodeFunctionData(fn.getFunction(item.name), returnData)
+            break
+          }
+        }
+      }
+      if (decodedCustomErrorInputs) {
+        msg = `\tThe transaction has been reverted to the initial state.\nError provided by the contract:`
+        msg += `\n${customError}`
+        msg += `\nParameters:`
+        msg += `\n${decodedCustomErrorInputs}`
+      }
+    }
+    if (!customError) {
       // It is the hash of Error(string)
-    if (returnData && (returnData.slice(0, 4).toString('hex') === '08c379a0')) {
+      if (returnData && (returnDataHex === '08c379a0')) {
         const abiCoder = new ethers.utils.AbiCoder()
         const reason = abiCoder.decode(['string'], returnData.slice(4))[0]
         msg = `\tThe transaction has been reverted to the initial state.\nReason provided by the contract: "${reason}".`
       } else {
         msg = '\tThe transaction has been reverted to the initial state.\nNote: The called function should be payable if you send value and the value you send should be less than your current balance.'
       }
+    }
     ret.error = true
   } else if (exceptionError === errorCode.STATIC_STATE_CHANGE) {
     msg = '\tState changes is not allowed in Static Call context\n'
     ret.error = true
   }
-  ret.message = `${error}${exceptionError}${msg}\tDebug the transaction to get more information.`
+  ret.message = `${error}\n${exceptionError}\n${msg}\Debug the transaction to get more information.`
   return ret
 }

libs/remix-lib/src/execution/txHelper.ts

@@ -38,6 +38,11 @@ export function encodeFunctionId (funABI) {
   return abi.getSighash(funABI.name)
 }
 
+export function getFunctionFragment (funABI): ethers.utils.Interface {
+  if (funABI.type === 'fallback' || funABI.type === 'receive') return null
+  return new ethers.utils.Interface([funABI])  
+}
+
 export function sortAbiFunction (contractabi) {
   // Check if function is constant (introduced with Solidity 0.6.0)
   const isConstant = ({ stateMutability }) => stateMutability === 'view' || stateMutability === 'pure'
@@ -97,10 +102,14 @@ export function extractSize (type) {
   return size ? size[2] : ''
 }
 
-export function getFunction (abi, fnName) {
+export function getError (abi, fnName) {
+  return getFromInterface(abi, fnName, 'error')
+}
+
+export function getFromInterface (abi, fnName, type) {
   for (let i = 0; i < abi.length; i++) {
     const fn = abi[i]
-    if (fn.type === 'function' && fnName === fn.name + '(' + fn.inputs.map((value) => {
+    if (fn.type === type && fnName === fn.name + '(' + fn.inputs.map((value) => {
       if (value.components) {
         const fullType = this.makeFullTypeDefinition(value)
         return fullType.replace(/tuple/g, '') // return of makeFullTypeDefinition might contain `tuple`, need to remove it cause `methodIdentifier` (fnName) does not include `tuple` keyword
@@ -114,6 +123,11 @@ export function getFunction (abi, fnName) {
   return null 
 }
 
+
+export function getFunction (abi, fnName) {
+  return getFromInterface(abi, fnName, 'function')
+}
+
 export function getFallbackInterface (abi) {
   for (let i = 0; i < abi.length; i++) {
     if (abi[i].type === 'fallback') {