`devtools::test_coverage_active_file()` and `devtools::test()` disagree on the error message to snapshot

[etiennebacher]

Repo with reprex: https://github.com/etiennebacher/bug.testthat.coverage (tested in Positron and RStudio)

> packageVersion("covr")
[1] ‘3.6.5.9001’
> packageVersion("devtools")
[1] ‘2.5.2.9000’
> packageVersion("testthat")
[1] ‘3.3.2.9000’

---

Setup:

• R/foo.R:

  f <- function(x) {
    if (x) {}
  }

• tests/testthat/test-foo.R:

  test_that("foo", {
    expect_snapshot(f(x = logical(0)), error = TRUE)
  })

• tests/testthat/_snaps/foo.md:

  # foo
  
    Code
      f(x = logical(0))
    Condition
      Error in `if (x) ...`:
      ! argument is of length zero
  

Bug:

1. Open tests/testthat/test-foo.R in your editor (so that it is detected as the "active file")
2. devtools::test() reports no issue
3. devtools::test_coverage_active_file() is not happy with the snapshot:

> devtools::test_coverage_active_file()
── Failure: foo ──────────────────────────────────────────────────────────────────────────────────────────
Snapshot of code has changed:
    old                            | new                               
[1] Code                           | Code                           [1]
[2]   f(x = logical(0))            |   f(x = logical(0))            [2]
[3] Condition                      | Condition                      [3]
[4]   Error in `if (x) ...`:       -   Error in `if (...) NULL`:    [4]
[5]   ! argument is of length zero |   ! argument is of length zero [5]
* Run testthat::snapshot_accept("foo") to accept the change.
* Run testthat::snapshot_review("foo") to review the change.
Error:
! Test failed with 1 failure and 0 successes.