Returns error when tx has not been mined

lib/exw3.ex

@@ -175,23 +175,20 @@ defmodule ExW3 do
 
   @spec keys_to_decimal(%{}, []) :: %{}
   def keys_to_decimal(map, keys) do
-    Map.new(
+    for k <- keys, into: %{}, do: {k, map |> Map.get(k) |> to_decimal()}
-      Enum.map(keys, fn k ->
-        {k, Map.get(map, k) |> to_decimal}
-      end)
-    )
   end
 
   @spec tx_receipt(binary()) :: %{}
   @doc "Returns transaction receipt for specified transaction hash(id)"
   def tx_receipt(tx_hash) do
     case call_client(:eth_get_transaction_receipt, [tx_hash]) do
+      {:ok, nil} ->
+        {:error, :not_mined}
+
       {:ok, receipt} ->
-        {:ok,
+        decimal_res = keys_to_decimal(receipt, ~w(blockNumber cumulativeGasUsed gasUsed))
-         Map.merge(
+
-           receipt,
+        {:ok, Map.merge(receipt, decimal_res)}
-           keys_to_decimal(receipt, ["blockNumber", "cumulativeGasUsed", "gasUsed"])
-         )}
 
       err ->
         {:error, err}
@@ -701,7 +698,8 @@ defmodule ExW3 do
     end
 
     def eth_send_helper(address, abi, method_name, args, options) do
-      encoded_options = ExW3.encode_options(
+      encoded_options =
+        ExW3.encode_options(
           options,
           [:gas, :gasPrice, :value, :nonce]
         )