From 2e4ed4fe8d02a181f215b4c9705a6493043943f5 Mon Sep 17 00:00:00 2001
From: chrisw000 <18504164+chrisw000@users.noreply.github.com>
Date: Sat, 16 Mar 2019 00:04:48 +0000
Subject: [PATCH] [Bug] Fix possible null exception when calling websocket stop
 (#191)

---
 CoinbasePro/Network/Authentication/Authenticator.cs | 7 +++++++
 CoinbasePro/Services/Products/ProductsService.cs    | 5 +++++
 CoinbasePro/WebSocket/WebSocket.cs                  | 8 +++++++-
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/CoinbasePro/Network/Authentication/Authenticator.cs b/CoinbasePro/Network/Authentication/Authenticator.cs
index 11321175..a9453ad8 100644
--- a/CoinbasePro/Network/Authentication/Authenticator.cs
+++ b/CoinbasePro/Network/Authentication/Authenticator.cs
@@ -13,6 +13,13 @@ public Authenticator(
             string unsignedSignature,
             string passphrase)
         {
+            if (string.IsNullOrEmpty(apiKey) || string.IsNullOrEmpty(unsignedSignature) ||
+                string.IsNullOrEmpty(passphrase))
+            {
+                throw new ArgumentException(
+                    $"{nameof(Authenticator)} requires parameters {nameof(apiKey)}, {nameof(unsignedSignature)} and {nameof(passphrase)} to be populated.");
+            }
+
             ApiKey = apiKey;
             UnsignedSignature = unsignedSignature;
             Passphrase = passphrase;
diff --git a/CoinbasePro/Services/Products/ProductsService.cs b/CoinbasePro/Services/Products/ProductsService.cs
index dc7ee85f..089b0edc 100644
--- a/CoinbasePro/Services/Products/ProductsService.cs
+++ b/CoinbasePro/Services/Products/ProductsService.cs
@@ -89,8 +89,13 @@ public async Task<IList<Candle>> GetHistoricRatesAsync(
 
                 candleList.AddRange(await GetHistoricRatesAsync(productPair, batchStart, batchEnd.Value, (int)granularity));
 
+                var previousBatchEnd = batchEnd;
                 batchEnd = candleList.LastOrDefault()?.Time;
 
+                if (previousBatchEnd == batchEnd) {
+                    break;
+                }
+
             } while (batchStart > start);
 
             return candleList;
diff --git a/CoinbasePro/WebSocket/WebSocket.cs b/CoinbasePro/WebSocket/WebSocket.cs
index 21384bba..b8d6eef4 100644
--- a/CoinbasePro/WebSocket/WebSocket.cs
+++ b/CoinbasePro/WebSocket/WebSocket.cs
@@ -36,7 +36,7 @@ public class WebSocket : IWebSocket
 
         private IWebSocketFeed webSocketFeed;
 
-        public WebSocketState State => webSocketFeed.State;
+        public WebSocketState State => webSocketFeed?.State ?? WebSocketState.None;
 
         public WebSocket(
             Func<IWebSocketFeed> createWebSocketFeed,
@@ -92,6 +92,12 @@ public void Start(
 
         public void Stop()
         {
+            if (webSocketFeed == null)
+            {
+                Log.Warning("Websocket did not attempt to stop as the feed has not been started yet");
+                return;
+            }
+
             if (webSocketFeed.State != WebSocketState.Open)
             {
                 throw new CoinbaseProWebSocketException(