Some operations fail for lists and strings

[sim1234]

Both
parse("c").update(["c"], 2)
parse("c").filter(lambda a: True, ["c"])

fail with

TypeError: list indices must be integers or slices, not str

I think it should do nothing instead because that patch does not make sense in context of that data.

Similar case with
parse("c").update("c", 2)
parse("c").filter(lambda a: True, "c")

but they fail with

TypeError: 'str' object does not support item assignment

and

TypeError: string indices must be integers

respectively.