Moved sys.exit out of the JSONRPCClient constructor

[ci integration]

raiden/network/rpc/client.py

@@ -1,6 +1,5 @@
 import copy
 import os
-import sys
 import warnings
 from binascii import unhexlify
 from json.decoder import JSONDecodeError
@@ -203,11 +202,7 @@ def __init__(
         except ConnectTimeout:
             raise EthNodeCommunicationError('couldnt reach the ethereum node')
 
-        supported, eth_node = is_supported_client(version)
-
-        if not supported:
-            print('You need a Byzantium enabled ethereum node. Parity >= 1.7.6 or Geth >= 1.7.2')
-            sys.exit(1)
+        _, eth_node = is_supported_client(version)
 
         sender = privatekey_to_address(privkey)
         transaction_count = web3.eth.getTransactionCount(to_checksum_address(sender), 'pending')

raiden/ui/cli.py

@@ -30,7 +30,7 @@
     to_normalized_address,
 )
 from mirakuru import ProcessExitedWithError
-from requests.exceptions import RequestException
+from requests.exceptions import ConnectTimeout, RequestException
 from web3 import Web3, HTTPProvider
 
 from raiden import constants
@@ -64,6 +64,7 @@
 from raiden.tasks import check_version
 from raiden.utils import (
     get_system_spec,
+    is_supported_client,
     merge_dict,
     split_endpoint,
     typing,
@@ -599,6 +600,16 @@ def run_app(
 
     web3 = Web3(HTTPProvider(eth_rpc_endpoint))
 
+    try:
+        node_version = web3.version.node  # pylint: disable=no-member
+    except ConnectTimeout:
+        raise EthNodeCommunicationError('couldnt reach the ethereum node')
+
+    supported, _ = is_supported_client(node_version)
+    if not supported:
+        print('You need a Byzantium enabled ethereum node. Parity >= 1.7.6 or Geth >= 1.7.2')
+        sys.exit(1)
+
     rpc_client = JSONRPCClient(
         web3,
         privatekey_bin,