The LANGSMITH_AGENT_* / project env vars can't address a run.
Raised for half an address, an invalid one, or an address beside a project.
Tracing entry points (@traceable, trace, tracing_context,
create_run) catch it, log it and leave the call untraced, so a bad
environment never breaks the code being traced. Explicit ingestion calls
(batch_ingest_runs, multipart_ingest) let it raise for runs that name no
destination, rather than drop part of a batch the caller built.
