SyntaxError: (IndexError) list index out of range

Hello,

we are using mako as template engine for generating latex-reports in tryton.
After an update of the source system from python 3.3 to python 3.5 migration, we get the following error:

Traceback (most recent call last):
  File "/usr/local/lib/python3.7/dist-packages/trytond/worker.py", line 108, in run_task
    Queue(task_id).run()
  File "/usr/local/lib/python3.7/dist-packages/trytond/ir/queue.py", line 169, in run
    instances, *self.data['args'], **self.data['kwargs'])
  File "/usr/local/lib/python3.7/dist-packages/trytond/model/modelview.py", line 672, in wrapper
    return func(cls, records, *args, **kwargs)
  File "/usr/local/lib/python3.7/dist-packages/trytond/modules/sale/sale.py", line 885, in process
    sale.create_invoice()
  File "/usr/local/lib/python3.7/dist-packages/trytond/modules/ebb_sale/sale.py", line 287, in create_invoice
    Invoice.post([invoice])
  File "/usr/local/lib/python3.7/dist-packages/trytond/modules/sale/invoice.py", line 20, in wrapper
    func(cls, invoices)
  File "/usr/local/lib/python3.7/dist-packages/trytond/modules/sale/invoice.py", line 87, in post
    super(Invoice, cls).post(invoices)
  File "/usr/local/lib/python3.7/dist-packages/trytond/modules/purchase/invoice.py", line 21, in wrapper
    func(cls, invoices)
  File "/usr/local/lib/python3.7/dist-packages/trytond/modules/purchase/invoice.py", line 98, in post
    super(Invoice, cls).post(invoices)
  File "/usr/local/lib/python3.7/dist-packages/trytond/model/modelview.py", line 672, in wrapper
    return func(cls, records, *args, **kwargs)
  File "/usr/local/lib/python3.7/dist-packages/trytond/model/workflow.py", line 36, in wrapper
    result = func(cls, filtered, *args, **kwargs)
nvoice.py", line 1383, in post.7/dist-packages/trytond/modules/account_invoice/i--More--
    invoice.print_invoice()
  File "/usr/local/lib/python3.7/dist-packages/trytond/modules/account_invoice/invoice.py", line 1292, in print_invoice
    InvoiceReport.execute([self.id], {})
  File "/usr/local/lib/python3.7/dist-packages/trytond/modules/latex_reports/latex.py", line 282, in execute
    mytemplate = Template(filename=report_path.replace('.odt','.tex'), cache_enabled=False, input_encoding='utf-8', output_encoding='utf-8')
  File "/usr/local/lib/python3.7/dist-packages/mako/template.py", line 338, in __init__
    module = self._compile_from_file(path, filename)
  File "/usr/local/lib/python3.7/dist-packages/mako/template.py", line 416, in _compile_from_file
    filename)
  File "/usr/local/lib/python3.7/dist-packages/mako/template.py", line 705, in _compile_text
    generate_magic_comment=template.disable_unicode)
  File "/usr/local/lib/python3.7/dist-packages/mako/template.py", line 685, in _compile
    node = lexer.parse()
  File "/usr/local/lib/python3.7/dist-packages/mako/lexer.py", line 241, in parse
    if self.match_expression():
  File "/usr/local/lib/python3.7/dist-packages/mako/lexer.py", line 402, in match_expression
    lineno=line, pos=pos)
  File "/usr/local/lib/python3.7/dist-packages/mako/lexer.py", line 140, in append_node
    node = nodecls(*args, **kwargs)
  File "/usr/local/lib/python3.7/dist-packages/mako/parsetree.py", line 194, in __init__
    self.code = ast.PythonCode(text, **self.exception_kwargs)
  File "/usr/local/lib/python3.7/dist-packages/mako/ast.py", line 40, in __init__
    expr = pyparser.parse(code.lstrip(), "exec", **exception_kwargs)
  File "/usr/local/lib/python3.7/dist-packages/mako/pyparser.py", line 48, in parse
    ), **exception_kwargs)
mako.exceptions.SyntaxException: (IndexError) list index out of range ("sale.invoice_address.party_name.replace('&','\\&')") in file '/tmp/trytond-latex-aevzw0qf/invoice.tex' at line: 80 char: 1

What we are wondering about: This does not occurs with the first time. It took some generations, e.g. is it possible, that somehow a caching is used and we should remove it?

We did test this with mako 1.1.3 and 1.0.7.

Thank you and best regards,
Hendrik

Start with the failing expression at line 80 of invoice.tex and trace Mako's path through template.py, lexer.py match_expression, parsetree.py PythonCode, and pyparser.py parse. Reproduce the intermittent failure with the reported Mako versions and determine whether caching affects it; done means the cause is isolated and the behavior is consistently explained.