missing test in split method when wrong path to bam is given

python3.6 scripts/intronSeeker.py split --input first_test_hisat2/HiSat2.Aligned.sortedByCoord.out.bam --reference data/Reduced_real_dataset/Test_set_Cele_contig-assembly.fasta -o first_test_hisat2  
[E::hts_open_format] Failed to open file first_test_hisat2/HiSat2.Aligned.sortedByCoord.out.bam
Traceback (most recent call last):
  File "scripts/intronSeeker.py", line 172, in 
    args.func(**param)
  File "/media/Stock/src/intronSeeker-master/scripts/intronResearch.py", line 77, in split_research
    res_gff,res_tmp = find_split(fastafilename,bamfilename) ;
  File "/media/Stock/src/intronSeeker-master/scripts/intronResearch.py", line 96, in find_split
    reads_list = [x.split("\t")[0] for x in pysam.idxstats(bamfilename).split("\n")[:-2]]
  File "/scratch2/src/anaconda3/envs/ISeeker_environment/lib/python3.6/site-packages/pysam/utils.py", line 75, in __call__
    stderr))
pysam.utils.SamtoolsError: 'samtools returned with error 1: stdout=, stderr=samtools idxstats: failed to open "first_test_hisat2/HiSat2.Aligned.sortedByCoord.out.bam": No such file or directory\n'