SuperCollider errors surface in the post window while the booted server keeps playing the last good nodes

SuperCollider separates language errors from server state. sclang prints syntax/parse errors on evaluate, ‘ERROR:’ plus a call stack for runtime errors, and scsynth prints server messages (‘FAILURE’, ‘node not found’, late messages) — all to the post window. Critically, a booted server keeps playing the last good nodes when a re-evaluation fails, so a broken JITLib edit silently doesn’t take. Performers must watch the post window actively; silence is not proof the edit succeeded. CmdPeriod (Cmd-.) or s.freeAll frees all nodes.

Examples

A JITLib Ndef re-eval with a syntax error leaves the old graph playing with no audible indication of failure. Only the post window shows the error.

Assessment

Describe what happens on the server when a SuperCollider re-evaluation fails mid-performance, and state which tool must be monitored to detect the failure.