kernel: Handle aborted connections instead of crashing

kernel/src/net/UnixSocket.cpp

@@ -159,6 +159,9 @@ Result<void> UnixSocket::connect(Registers* regs, int flags, struct sockaddr* ad
         break;
     }
 
+    // This means that the connection was established, but closed before this thread could run again.
+    if (m_state == Reset) return err(ECONNABORTED);
+
     check(m_state == Connected);
     check(m_peer);