fixes #244

nimbus/vm/interpreter_dispatch.nim

@@ -300,3 +300,7 @@ proc executeOpcodes(computation: BaseComputation) =
     let msg = getCurrentExceptionMsg()
     computation.setError(&"Opcode Dispatch Error msg={msg}, depth={computation.msg.depth}", true)
   computation.nextProc()
+
+  if computation.isError():
+    if computation.tracingEnabled: computation.traceError()
+    debug "executeOpcodes error", msg=computation.error.info

nimbus/vm/transaction_tracer.nim

@@ -120,9 +120,10 @@ proc traceError*(tracer: var TransactionTracer, c: BaseComputation) =
     j["error"] = %(c.error.info)
     trace "Error", json = j.pretty()
 
-  # TODO: figure out how to get gasCost
-  # when contract execution failed before traceOpCodeEnded called
-  # because exception raised
-  #j["gasCost"] = %
+    # even though the gasCost is incorrect,
+    # we have something to display,
+    # it is an error anyway
+    let gasRemaining = j["gas"].getInt()
+    j["gasCost"] = %(gasRemaining - c.gasMeter.gasRemaining)
 
   tracer.trace["failed"] = %true

nimbus/vm_state_transactions.nim

@@ -74,7 +74,7 @@ proc execComputation*(computation: var BaseComputation): bool =
     for deletedAccount in computation.accountsForDeletion:
       db.deleteAccount deletedAccount
       inc suicidedCount
-    
+
     # FIXME: hook this into actual RefundSelfDestruct
     const RefundSelfDestruct = 24_000
     computation.gasMeter.refundGas(RefundSelfDestruct * suicidedCount)
@@ -82,8 +82,6 @@ proc execComputation*(computation: var BaseComputation): bool =
   result = computation.isSuccess
   if result:
     computation.vmState.addLogs(computation.logEntries)
-  else:
-    if computation.tracingEnabled: computation.traceError()
 
 proc refundGas*(computation: BaseComputation, tx: Transaction, sender: EthAddress): GasInt =
   let