Decoder crash for Stereo EVS Downmix with FEC in gaus_dec_fx()

Basic info

• Encoder (float): d9fdb374
• Decoder: 7fdbf113

Bug description

The complexity measurement job for Stereo EVS downmix results in a decoder crash with an assert:

Assertion failed: (0), function L_shl, file basop32.c, line 2582.

Ways to reproduce

Bitstream: ltv48_STEREO_StereoDmxEvs_b06_64_dtx_amr_evs_wb_rs_fer_ep_10pct_fer_g192.192.zip

./IVAS_cod -stereo_dmx_evs -dtx -max_band wb scripts/switchPaths/sw_amrwb_evs.bin 16 ltv48_STEREO_16_STEREO.pcm bit
eid-xor -vbr -fer bit bit_err 
./IVAS_dec 16 bit_err out

Further crashes in the job can be reproduced with the runIvasCodec.py script:

./scripts/runIvasCodec.py -p scripts/config/ci_linux_ltv.json -f ci/complexity_measurements/ep_10pct_fer.g192 -x StereoDmxEvs_b08_0_dtx_wb_cbr 

The -x argument should be used without the filename prefix and the error pattern suffix, e.g.:

ltv48_STEREO_StereoDmxEvs_b08_0_dtx_wb_cbr_fer_ep_10pct_fer_g192
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^