make Debugger.prototype.debug returns a Promise

remix-debug/src/debugger/debugger.js

@@ -72,31 +72,41 @@ Debugger.prototype.debug = function (blockNumber, txNumber, tx, loadingCb) {
   const self = this
   let web3 = this.debugger.web3
 
+  return new Promise((resolve, reject) => {
   if (this.debugger.traceManager.isLoading) {
-    return
+      return resolve()
   }
 
   if (tx) {
     if (!tx.to) {
       tx.to = traceHelper.contractCreationToken('0')
     }
-    return self.debugTx(tx, loadingCb)
+      self.debugTx(tx, loadingCb)
+      return resolve()
   }
 
   try {
     if (txNumber.indexOf('0x') !== -1) {
       return web3.eth.getTransaction(txNumber, function (_error, result) {
+          if (_error) return reject(_error)
+          if (!result) return reject('cannot find transaction ' + txNumber)
         let tx = result
         self.debugTx(tx, loadingCb)
+          return resolve()
       })
     }
     web3.eth.getTransactionFromBlock(blockNumber, txNumber, function (_error, result) {
+        if (_error) return reject(_error)
+        if (!result) return reject('cannot find transaction ' + blockNumber + ' ' + txNumber)
       let tx = result
       self.debugTx(tx, loadingCb)
+        return resolve()
     })
   } catch (e) {
     console.error(e.message)
+      return reject(e.message)
   }
+  })
 }
 
 Debugger.prototype.debugTx = function (tx, loadingCb) {