`redact: true` makes Ecto derive an Inspect impl at the `schema` line.
Elixir 1.20.4 emits that whole derived impl on that one line, and OTP 27's
coverage instrumentation (sys_coverage) turns it into invalid Erlang
("variable '_2' unsafe in 'case'"), so `mix test --cover` aborted for the whole
app before reporting anything. Minimal repro, no Ecto needed:
`@derive Inspect` on a plain struct fails on Elixir 1.20.4 + OTP 27.3.4.19 and
works on Elixir 1.18.3 + the same OTP.
Writing the impl out by hand, one expression per line, keeps `inspect/1`
output byte-identical (Ecto/Elixir render redacted fields as
`#Mod<..., ...>`) and keeps redaction pinned by the existing test, and lets the
coverage sensor land. Revisit when the Elixir/OTP pins change.
Willem van den Ende
a9a02aa9ba