Training Gigispeech problem in Kaldi

Hi dear author,

I only want to train a small acoustics model use Gigaspeech, but I encountered some problems when I run Gigaspeech recipe in Kaldi.

.if [ $stage -le 2 ]; then
echo "======Train lm START | current time : `date +%Y-%m-%d-%T`=============="
mkdir -p $lm_dir || exit 1;
sed 's|\t| |' data/$train_combined/text |\
cut -d " " -f 2- > $lm_dir/corpus.txt || exit 1;
echo "break point1"
local/lm/train_lm.sh \
--cmd "$train_cmd" --lm-order $lm_order \
$lm_dir/corpus.txt $lm_dir || exit 1;
echo "break point2"
echo "======Train lm END | current time : `date +%Y-%m-%d-%T`================"
fi

this step let me install SRILM and train a language model(when I train librispeech, I didn't do these two things), is it necessary?(I only want to train a acoustics model and don't need compute wer), whatever, I skip this step

Thanks very much!