There was one call to a throwing function inside
`checkArticles(in:correspondToStreamItemsIn:)` which was not
appropriately marked with `try`. Add that keyword, and then bubble out
the chain of errors through additional layers of helpers to the
enclosing test:
* This `checkArticles` variant was called by two others
* …one of which was used in `testAddNewFeedSuccess()`
* …another of which was used in various `verify` sync helpers
* …which were referenced from `testSyncing()`, a test case method
None of these involved any particular async hoops to jump through, and
since the top-level callers were all test functions, we can count on
XCTest to handle any errors thrown — no additional `catch` or handling
on our part is necessary.
Two more cases of completion blocks taking Results, requiring a
do/catch/Result.get() to unwrap.
This commit deliberately leaves one build error for a more comprehensive
fix, since it occurs in a helper function that will have broader
fallout.