Line 10283 same issue as 10393: when instrumentProgram is
undefined (section cloned tracks), program defaults to 0.
_playNoteFluid calls program_change(ch,0) on FluidSynth,
which loads program 0 from whatever SoundFont is loaded
(MAIN session's SF). Fix: pass undefined -> oscillator
fallback for all tracks without assigned instrument.
3dtours
2f2f84066c