Assert in ivas_hq_phase_ecu_fx in decoder for 4 discrete ISM fixed to fixed with LTV +10dB input

Basic info

• Fixed point:
  • Encoder (fixed): 4263280a
  • Decoder (fixed): 4263280a

Bug description

This is a crash in this daily job https://forge.3gpp.org/rep/sa4/audio/ivas-basop/-/jobs/598383

There is an assert happening within FEC_HQ_phase_ecu_fx.c. It happens in frame 3812. Stack trace below:

Ways to reproduce

Use the command-line below and the bitstream from Box (to simplify having +10 dB input)

Box folder: ...\Box_EXTERNAL_IVAS_BASOP_VERIFICATION\issues\issue-2170

./IVAS_dec BINAURAL 48 debug_error.bit out.wav

The original issue has object editing present but this happens even without it.