Readonlyfelltrue when the requested landmark (a referenced stage/insert) was absent and the
tap fell through to the previous processor's output. The fall-through target is
always a valid port (recommendation 2/3 of the WING/SSL comparison). A pre-the-head
tap (index === CHAIN_INPUT) is not a fall-through — it is the legitimate input.
ReadonlyindexChain index of the tapped processor, or CHAIN_INPUT for the strip source.
Optional ReadonlyprocessorThe processor at index; undefined when index === CHAIN_INPUT (the source).
A resolved tap: the position whose output port the send picks off.
indexis the chain index of the tapped processor, or CHAIN_INPUT (-1) meaning the strip source boundary — the signal entering the chain, before any processor (a "Pre-X" tap whose anchor sits at the very head, e.g. a pre-fader monitor send on a fader-first chain). The engine readsindexto find the port and the latency-to-here.