# Buggy code
def focus_changed(self):
    if self.master.view.focus.flow:
        self.tabs = [
            (self.tab_request, self.view_request),
            (self.tab_response, self.view_response),
            (self.tab_details, self.view_details),
        ]
    self.show()


# Traceback (AttributeError)
Traceback (most recent call last):
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/tools/console/master.py", line 216, in run
self.loop.run()
File "/home/user/venv/lib/python3.5/site-packages/urwid/main_loop.py", line 278, in run
self._run()
File "/home/user/venv/lib/python3.5/site-packages/urwid/main_loop.py", line 376, in _run
self.event_loop.run()                                                                                       [*:8080]
File "/home/user/venv/lib/python3.5/site-packages/urwid/main_loop.py", line 682, in run
self._loop()
File "/home/user/venv/lib/python3.5/site-packages/urwid/main_loop.py", line 719, in _loop
self._watch_files[fd]()
File "/home/user/venv/lib/python3.5/site-packages/urwid/raw_display.py", line 393, in <lambda>
event_loop, callback, self.get_available_raw_input())
File "/home/user/venv/lib/python3.5/site-packages/urwid/raw_display.py", line 493, in parse_input
callback(processed, processed_codes)
File "/home/user/venv/lib/python3.5/site-packages/urwid/main_loop.py", line 403, in _update
self.process_input(keys)
File "/home/user/venv/lib/python3.5/site-packages/urwid/main_loop.py", line 503, in process_input
k = self._topmost_widget.keypress(self.screen_size, k)
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/tools/console/window.py", line 312, in keypress
k
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/tools/console/keymap.py", line 130, in handle
return self.executor(b.command)
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/tools/console/commandexecutor.py", line 17, in __call__
ret = self.master.commands.call(cmd)
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/command.py", line 221, in call
return self.call_args(parts[0], parts[1:])
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/command.py", line 212, in call_args
return self.commands[path].call(args)
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/command.py", line 101, in call
ret = self.func(*pargs)
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/command.py", line 251, in wrapper
return function(*args, **kwargs)
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/addons/view.py", line 413, in remove
self.sig_view_remove.send(self, flow=f, index=idx)
File "/home/user/venv/lib/python3.5/site-packages/blinker/base.py", line 267, in send
for receiver in self.receivers_for(sender)]
File "/home/user/venv/lib/python3.5/site-packages/blinker/base.py", line 267, in <listcomp>
for receiver in self.receivers_for(sender)]
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/addons/view.py", line 566, in _sig_view_remove
self.flow = None
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/addons/view.py", line 547, in flow
self.sig_change.send(self)
File "/home/user/venv/lib/python3.5/site-packages/blinker/base.py", line 267, in send
for receiver in self.receivers_for(sender)]
File "/home/user/venv/lib/python3.5/site-packages/blinker/base.py", line 267, in <listcomp>
for receiver in self.receivers_for(sender)]
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/tools/console/window.py", line 209, in focus_changed
i.call("focus_changed")
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/tools/console/window.py", line 118, in call
getattr(self.top_window(), name)(*args, **kwargs)
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/tools/console/flowview.py", line 231, in focus_changed
self.body.focus_changed()
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/tools/console/flowview.py", line 58, in focus_changed
self.show()
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/tools/console/tabs.py", line 52, in show
txt = self.tabs[i][0]()
File "/mnt/c/Users/user/git/mitmproxy/mitmproxy/tools/console/flowview.py", line 69, in tab_request
if self.flow.intercepted and not self.flow.response:
AttributeError: 'NoneType' object has no attribute 'intercepted'

# Fixed code
def focus_changed(self):
    if self.master.view.focus.flow:
        self.tabs = [
            (self.tab_request, self.view_request),
            (self.tab_response, self.view_response),
            (self.tab_details, self.view_details),
        ]
        self.show()
    else:
        self.master.window.pop()