Hello. I have a dataset with lower coverage than expected, and quite sparse data. Most output files are written normally, but the vcf is not. When running step 7 on version 0.6.24, the "building vcf file" sub-step is interrupted very early with this error: "TypeError(ufunc 'add' did not contain a loop with signature matching types dtype('S21') dtype('S21') dtype('S21'))". Any idea of how I can get the vcf file? Thanks.