Fix traceback raised on an expression list assignment

[ericwb]

When there is an assignment using a pattern_list and expression_list, the current code will iterate through each assignment. However, the current code assumes it can use context['node'], which is not the expected node during the parse.

: Language(path, name) is deprecated. Use Language(ptr, name) instead.
  warn("{} is deprecated. Use {} instead.".format(old, new), FutureWarning)
logging initialized
Working on file: tests/unit/parsers/examples/expression_list_assignment.py
Exception occurred when executing rules against tests/unit/parsers/examples/expression_list_assignment.py. Run "precli --debug tests/unit/parsers/examples/expression_list_assignment.py" to see the full traceback.
  Exception string: cannot access local variable 'func_node' where it is not associated with a value
  Exception traceback: Traceback (most recent call last):
  File "/Users/ericwb/workspace/precli/precli/core/run.py", line 127, in parse_file
    return parser.parse(artifact)
           ^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/ericwb/workspace/precli/precli/parsers/__init__.py", line 99, in parse
    self.visit([tree.root_node])
  File "/Users/ericwb/workspace/precli/precli/parsers/__init__.py", line 124, in visit
    visitor_fn(node.children)
  File "/Users/ericwb/workspace/precli/precli/parsers/python.py", line 31, in visit_module
    self.visit(nodes)
  File "/Users/ericwb/workspace/precli/precli/parsers/__init__.py", line 124, in visit
    visitor_fn(node.children)
  File "/Users/ericwb/workspace/precli/precli/parsers/__init__.py", line 124, in visit
    visitor_fn(node.children)
  File "/Users/ericwb/workspace/precli/precli/parsers/python.py", line 98, in visit_assignment
    self.visit_assignment(
  File "/Users/ericwb/workspace/precli/precli/parsers/python.py", line 145, in visit_assignment
    func_node=func_node,
              ^^^^^^^^^
UnboundLocalError: cannot access local variable 'func_node' where it is not associated with a value