A SuperCollider UGen name that is miscased or not installed posts 'not understood' rather than playing

SuperCollider class and UGen names are case-sensitive, and plugin UGens (sc3-plugins) are not present in a core install. Writing sinosc instead of SinOsc, or referencing a class the install lacks (e.g. Decimator), posts ‘Message ‘ar’ not understood’ or ‘nil does not understand’ rather than making sound. The fix is to verify names against the core UGen/class lists and correct the case; plugin UGens must be avoided or flagged in a rig that lacks sc3-plugins. This is the SuperCollider face of the name-hallucination failure mode.

Examples

sinosc.ar(440) → ‘Message ‘ar’ not understood’. Fix: SinOsc.ar(440). Decimator.ar(...) fails unless sc3-plugins is installed.

Assessment

State what post message a miscased or uninstalled SuperCollider UGen produces, and name the reference the performer should check to correct it.