@brief returns a const reverse iterator to the last element @sa https://json.nlohmann.me/api/basic_json/crbegin/

@brief returns a const reverse iterator to one before the first @sa https://json.nlohmann.me/api/basic_json/crend/

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Note: This function is marked with noexcept but may theoretically encounter an exception and terminate the program if locking the mutex fails. If this