RPC mode iterated readJsonl(Bun.stdin.stream()), where JSON parsing runs
inside the generator. A parse error thrown from the generator escaped the
frame loop's try/catch (which only wrapped dispatch), unwound runRpcMode,
and exited the process on any non-JSON stdin line.
Read raw lines via readLines and JSON.parse each inside the existing
try/catch so a malformed line emits a Failed to parse command error frame
and the loop keeps running. Shared readJsonl stays strict for session-file
reads.
Fixes#5194
Wolfgang Schoenberger