JS-engine error-message format contradicts the UA engine
br.error_engine_vs_ua · convicts
browserlayer
coherencecategory
4evaders caught
What it catches
CreepJS: V8/SpiderMonkey/JSC produce distinct TypeError messages; the engine's own message generator is far harder to spoof than navigator.vendor
Signals it reads
browser.error_engine_mismatch
How it fires
present
Evaders it caught 4
Bypassed by 10
Frontier evaders that reach the detector uncaught (scored only suspicious, defeating every convicting tell) — this check is not one that stops them. The red-team frontier this detection still has to convict.