include nonce in JsonRpcProviderError

This would allow applications to use the nonce in case of an error, eg cancel the transaction to prevent stuck txs from occurring

ethers/providers/jsonrpc.nim

@@ -24,6 +24,7 @@ type
     provider: JsonRpcProvider
     address: ?Address
   JsonRpcProviderError* = object of ProviderError
+    nonce*: ?UInt256
   JsonRpcSubscription* = ref object of Subscription
     subscriptions: JsonRpcSubscriptions
     id: JsonNode
@@ -34,7 +35,19 @@ proc raiseJsonRpcProviderError(message: string) {.upraises: [JsonRpcProviderErro
     message = parseJson(message){"message"}.getStr
   except Exception:
     discard
-  raise newException(JsonRpcProviderError, message)
+  let ex = newException(JsonRpcProviderError, message)
+  ex[].nonce = nonce
+  raise ex
+
+template convertError(nonce = none UInt256, body) =
+  try:
+    body
+  except JsonRpcError as error:
+    raiseProviderError(error.msg, nonce)
+  # Catch all ValueErrors for now, at least until JsonRpcError is actually
+  # raised. PR created: https://github.com/status-im/nim-json-rpc/pull/151
+  except ValueError as error:
+    raiseProviderError(error.msg, nonce)
 
 template convertError(body) =
   try:

testmodule/providers/jsonrpc/testJsonRpcProvider.nim

@@ -99,3 +99,20 @@ for url in ["ws://localhost:8545", "http://localhost:8545"]:
         discard await provider.subscribe(proc(_: Block) = discard)
       expect JsonRpcProviderError:
         discard await provider.getSigner().sendTransaction(Transaction.example)
+
+    test "JsonRpcProviderError contains nonce":
+      let signer = provider.getSigner()
+      var transaction = Transaction.example
+      var populated: Transaction
+      try:
+        populated = await signer.populateTransaction(transaction)
+        populated.chainId = some 0.u256
+        let confirming = signer.sendTransaction(populated).confirm(1)
+        await sleepAsync(100.millis) # wait for tx to be mined
+        await provider.mineBlocks(1)
+        discard await confirming
+      except JsonRpcProviderError as e:
+        check e.nonce.isSome
+        check e.nonce == populated.nonce
+        return
+      fail()