causeMessage(cause: unknown): string
Extracts a caller-facing message from an unknown thrown value.
The one-line counterpart of serializeError: that turns a thrown
value into a structured record for a log sink, this turns it into the
sentence that goes inside another error's message.
It is published because two packages must produce the SAME sentence and
§2.2 forbids the import that would let one read the other's copy.
resolveRegistryEntry uses it for a factory that threw, and
@setu-ts/scheduler-plugin for a declared job that could not be scheduled —
the two arms of one jobs option, which have to be indistinguishable to an
operator reading the failure. A local copy in each was byte-identical and
free to drift.