Missing test on the presence of the fasta file

(ISeeker_environment) cklopp@beraldi:/scratch2/src/intronSeeker-master$ python3.6 scripts/intronSeeker.py split --input first_test_hisat2/first_test.Aligned.sortedByCoord.out.bam --reference data/Reduced_real_dataset/Test_set_Cele_contig-assembly.fasta -o first_test_hisat2b
mkdir: cannot create directory 'first_test_hisat2b_split': File exists
[E::fai_retrieve] Failed to retrieve block: unexpected end of file
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 114, in find_split
    reference = ref_dict.fetch(id)
  File "pysam/libcfaidx.pyx", line 317, in pysam.libcfaidx.FastaFile.fetch
FileNotFoundError: [Errno 2] b'No such file or directory'