Use the correct data structures for exceptions

[NyanHelsing]

Ticket

No ticket

Purpose

A tuple is the correct data structure for cases where the position in
the structure has meaning rather than being ordered, so a list of tuples
is the correct data structure for the stack here.

A couple links to relevant discussion:

Though tuples may seem similar to lists, they are often used in different situations and for different purposes. Tuples are immutable, and usually contain a heterogeneous sequence of elements that are accessed via unpacking (see later in this section) or indexing (or even by attribute in the case of namedtuples). Lists are mutable, and their elements are usually homogeneous and are accessed by iterating over the list.

https://docs.python.org/3/tutorial/datastructures.html#tuples-and-sequences
http://jtauber.com/blog/2006/04/15/python_tuples_are_not_just_constant_lists/
https://stackoverflow.com/questions/626759/whats-the-difference-between-lists-and-tuples

Changes

Replace lists where tuples are more correct

Side effects

Doubtful

QA Notes

N/A

Deployment Notes

N/A

[coveralls]

Coverage remained the same at 71.218% when pulling 18d2ad8 on birdbrained:ft/use-correct-types-for-errors into d15d322 on CenterForOpenScience:develop.

[cslzchen]

Looks good to me. 🎆 Tuple makes more sense than list here. Just one more thing to double check. Do we have any usage of the self.attr_stack that may expecting a list for the error and message? If so, we need to update them as well.