René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Tab completion for dict key causes crash","articleBody":"This issue is not reproducible with several different `dict`s that I've tried, but it can be reproduced with the `dict` below.\r\n\r\n```\r\nmy_dict = {\r\n'Circle': {'Ellipse',\r\n           'Shape',\r\n           'ShapeDriver'},\r\n\r\n'Ellipse': {'Shape'},\r\n\r\n'Rectangle': {'Shape'},\r\n\r\n'Shape': {'Circle'},\r\n\r\n'ShapeDriver': {'Circle',\r\n                'Ellipse',\r\n                'Shape'},\r\n\r\n'Square': {'Rectangle'}\r\n}\r\n```\r\n\r\nSteps to recreate:\r\n1. create new `dict`\r\n2. type `my_dict[`\r\n3. press \u003ctab\u003e key to use tab-completion\r\n4. crash\r\n\r\n```\r\n~ % bpython\r\nbpython version 0.21 on top of Python 3.8.2 /Library/Developer/CommandLineTools/usr/bin/python3\r\n\u003e\u003e\u003e my_dict = {\r\n... 'a/Circle': {'Ellipse',\r\n...            'Shape',\r\n...            'ShapeDriver'},\r\n... \r\n... 'a/Ellipse': {'Shape'},\r\n... \r\n... 'a/Rectangle': {'Shape'},\r\n... \r\n... 'a/Shape': {'Circle'},\r\n... \r\n... 'a/ShapeDriver': {'Circle',\r\n...                 'Ellipse',\r\n...                 'Shape'},\r\n... \r\n... 'a/Square': {'Rectangle'}\r\n... }\r\n\u003e\u003e\u003e my_dict['b/banana']\r\nTraceback (most recent call last):\r\n  File \"/Users/arian/Library/Python/3.8/bin/bpython\", line 8, in \u003cmodule\u003e\r\n    sys.exit(main())\r\n  File \"/Users/arian/Library/Python/3.8/lib/python/site-packages/bpython/curtsies.py\", line 201, in main\r\n    exit_value = repl.mainloop(True, paste)\r\n  File \"/Users/arian/Library/Python/3.8/lib/python/site-packages/bpython/curtsies.py\", line 121, in mainloop\r\n    self.process_event_and_paint(e)\r\n  File \"/Users/arian/Library/Python/3.8/lib/python/site-packages/bpython/curtsies.py\", line 85, in process_event_and_paint\r\n    self.process_event(e)\r\n  File \"/Users/arian/Library/Python/3.8/lib/python/site-packages/bpython/curtsiesfrontend/repl.py\", line 615, in process_event\r\n    return self.process_key_event(e)\r\n  File \"/Users/arian/Library/Python/3.8/lib/python/site-packages/bpython/curtsiesfrontend/repl.py\", line 757, in process_key_event\r\n    self.on_tab()\r\n  File \"/Users/arian/Library/Python/3.8/lib/python/site-packages/bpython/curtsiesfrontend/repl.py\", line 891, in on_tab\r\n    cursor_and_line = self.matches_iter.substitute_cseq()\r\n  File \"/Users/arian/Library/Python/3.8/lib/python/site-packages/bpython/repl.py\", line 297, in substitute_cseq\r\n    self.update(\r\n  File \"/Users/arian/Library/Python/3.8/lib/python/site-packages/bpython/repl.py\", line 318, in update\r\n    self.start, self.end, self.current_word = self.completer.locate(\r\nTypeError: cannot unpack non-iterable NoneType object\r\n```\r\n\r\nImage below so you can see the colors as well:\r\n![image](https://user-images.githubusercontent.com/71411328/134820762-07de5cae-70b0-486e-8b7a-ac529cf8533e.png)\r\n","author":{"url":"https://github.com/arian-deimling","@type":"Person","name":"arian-deimling"},"datePublished":"2021-09-26T19:01:42.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/917/bpython/issues/917"}