Handle rare race conditions

src/org/omegazero/net/common/SelectorHandler.java

@@ -167,7 +167,15 @@ public abstract class SelectorHandler {
 					Iterator<SelectionKey> iterator = this.selector.selectedKeys().iterator();
 					while(iterator.hasNext()){
 						SelectionKey key = iterator.next();
-						this.handleSelectedKey(key);
+						// CancelledKeyException is likely caused by an extremely rare race condition when one thread is executing this handleSelectedKey handler
+						// while another thread called close() on the channel. The handler likely attempts to interact with the now canceled key and causes this exception
+						try{
+							this.handleSelectedKey(key);
+						}catch(java.nio.channels.CancelledKeyException e){
+							SelectableChannel channel = key.channel();
+							logger.warn("Caught CancelledKeyException on channel ", channel);
+							channel.close();
+						}
 						iterator.remove();
 					}
 				}

src/org/omegazero/net/server/TCPServer.java

@@ -167,6 +167,10 @@ public abstract class TCPServer extends InetConnectionSelector implements InetSe
 		if(key.isAcceptable()){
 			ServerSocketChannel serverChannel = (ServerSocketChannel) key.channel();
 			SocketChannel socketChannel = serverChannel.accept();
+			if(socketChannel == null){
+				logger.warn("Received OP_ACCEPT but no socket is available");
+				return;
+			}
 
 			InetConnection conn = this.handleConnection(socketChannel);
 			conn.setOnLocalClose(super::onConnectionClosed);
@@ -189,7 +193,8 @@ public abstract class TCPServer extends InetConnectionSelector implements InetSe
 					conn.handleData(data);
 				});
 			}
-		}
+		}else
+			throw new RuntimeException("Invalid key state");
 	}