Segmentation fault upon print_dict

[Unniboy]

Requesting help to get past the segmentation fault.
libyang: v2.1.148
libyang-python: v2.8.4

The following set of operations result in segmentation fault. Intermediate unrelated steps modifying dtree(play_tree after loading classroom) could be a premonition of the eventual segmentation fault.
Couldn't see anything wrong with the yangs themselves, given dtree was generated.

>>> import libyang
>>> ctx = libyang.Context('poc')
>>>
>>> play_mod= ctx.load_module('playroom')
>>> play_dict={'playroom-container':{'playroom-list': [{'name': 'dodge', 'play': 'gogogo'}]}}
>>> play_tree = play_mod.parse_data_dict(play_dict, validate=False)
>>>
>>> play_tree.print_dict()
{'playroom-container': {'playroom-list': [{'name': 'dodge', 'play': 'gogogo'}]}}
>>>
>>>
>>> class_mod= ctx.load_module('classroom')
>>>
>>>
>>> play_tree.print_dict()
{'playroom-container': {}}
>>>
>>>
>>> class_dict={'classroom-container': {'classroom-list': [{'name': 'grade5', 'teacher-present': True, 'shout': 'wohoo'}]}}
>>> class_tree = class_mod.parse_data_dict(class_dict, validate=False)
>>>
>>>
>>> class_tree.print_dict()
{'classroom-container': {'classroom-list': [{'name': 'grade5', 'teacher-present': True, 'shout': 'wohoo'}]}}
>>>
>>>
>>> play_tree.print_dict()
Segmentation fault

The yang definitions are as below:

module str-types {
	namespace "http://str-types";
	prefix "str-types";
	typedef name-type {
		type string;
	}
	grouping chaos {
		leaf shout {
			type name-type;
		}
	}
}

module playroom {
	namespace "http://playroom";
	prefix "playroom";
	import str-types { prefix str-types; }
	container playroom-container {
		list playroom-list {
			key "name";
			leaf name {
				type string;
			}

			leaf play {
				type str-types:name-type;
			}
		}
	}
}

module classroom {
	namespace "http://classroom";
	prefix "classroom";
	import str-types { prefix str-types; }
	container classroom-container {
		list classroom-list {
			key "name";
			leaf name {
				type string;
			}
			leaf teacher-present {
				type boolean;
			}

			uses str-types:chaos {
				when "not(./teacher-present) or ./teacher-present = 'false'";
			}
			leaf study {
				when "../teacher-present and ../teacher-present = 'true'";
				type str-types:name-type;
			}
		}
	}
}