From 7562d9bbf844bf927269541d4238002a3b9987f8 Mon Sep 17 00:00:00 2001
From: catbref <misc-github@talk2dom.com>
Date: Tue, 1 Dec 2020 17:22:40 +0000
Subject: [PATCH] Fix potential NPE when closing a websocket that failed to
 open properly

---
 src/main/java/org/qortal/api/websocket/ApiWebSocket.java | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/qortal/api/websocket/ApiWebSocket.java b/src/main/java/org/qortal/api/websocket/ApiWebSocket.java
index 87ee16cd..f6a439ea 100644
--- a/src/main/java/org/qortal/api/websocket/ApiWebSocket.java
+++ b/src/main/java/org/qortal/api/websocket/ApiWebSocket.java
@@ -107,7 +107,9 @@ abstract class ApiWebSocket extends WebSocketServlet {
 
 	public void onWebSocketClose(Session session, int statusCode, String reason) {
 		synchronized (SESSIONS_BY_CLASS) {
-			SESSIONS_BY_CLASS.get(this.getClass()).remove(session);
+			List<Session> sessions = SESSIONS_BY_CLASS.get(this.getClass());
+			if (sessions != null)
+				sessions.remove(session);
 		}
 	}