Problem: when required dependencies (GNU time/timeout, Python env) are
missing, config.setup() throws a raw error() that surfaces as a Lua
traceback. On macOS without coreutils the message is also redundant
("GNU time not found: GNU time not found") and offers no install hint.
Solution: wrap config.setup() in pcall inside ensure_initialized(),
strip the Lua source-location prefix, and emit a vim.notify at ERROR
level. Add Darwin-specific install guidance to the GNU time/timeout
not-found messages. Pass capability reasons directly instead of
wrapping them in a redundant outer message.