UnboundLocalError: local variable 'lang_addr' referenced before assignment

[qaip]

Describe the bug

sc-web/server/handlers/api.py

Lines 78 to 79 in 223e9d2

	if lang_arg:
	lang_addr = ScAddr(int(lang_arg))

The lang_addr variable is declared only in case of lang_arg's existence, but is referenced later regardless.

sc-web/server/handlers/api.py

Lines 123 to 124 in 223e9d2

	if lang_addr:
	construction.create_edge(sc_types.EDGE_ACCESS_CONST_POS_PERM, 'trans_cmd_addr', lang_addr, 'arc_addr_4')

To Reproduce
Steps to reproduce the behavior:

1. Make a (regular) POST request to /api/question/answer/translate/ with no lang parameter passed.
2. See error

Expected behavior
Either a success response or a response indicating that "lang is a required parameter" or "some required parameters are missing".