Fix some Rubocop violations

Author: rastating

payloads/reverse_tcp.rb

@@ -81,11 +81,11 @@ def constants
 
     def obfuscated_variables
       super +
-        %w(
+        %w[
           ip port chunk_size write_a error_a shell pid sock
           errno shell pid sock errno errstr descriptor_spec
           process pipes read_a error_a num_changed_sockets input
-        )
+        ]
     end
 
     def raw
@@ -128,7 +128,7 @@ def post_exploit(mod)
 
       if @session_started
         begin
-          @network_thread.join if @network_thread
+          @network_thread&.join
         rescue SignalException
           puts
           mod.emit_warning 'Caught kill signal', true
@@ -143,7 +143,7 @@ def post_exploit(mod)
 
     def cleanup
       self.queued_commands = []
-      @network_thread.exit if @network_thread
+      @network_thread&.exit
       @server.close if @server && !@server.closed?
     end
   end