Parsing gene mutation burden fails on -d:release

parse_burden.nim

import os
import tables
import strutils
import sequtils
import algorithm
import streams
import hts

proc main() =
    ## Open VCF file
    var vcf : VCF
    assert open(vcf, paramStr(1))
    ## Table
    var burden_table = initTable[string, seq[int32]]()
    ## Annotation holders
    var
        ann_info  : string
        anns : seq[string]
        vals : seq[string]
        gt_values : seq[int32] = newSeq[int32](vcf.n_samples)
        alt_count : seq[int32] = newSeq[int32](vcf.n_samples)
        genotypes : Genotypes
        iter: int = 0
    ## loop over variant vords
    for v in vcf:
        if v.info.get("ANN", ann_info) != Status.OK:
            continue
        genotypes = genotypes(v.format, gt_values)

        for ann in split(ann_info, ","):
            vals = split(ann, "|")
            
            var idx = find(v.ALT, vals[0]) + 1
            var i = 0
            fill(alt_count, 0)
            for g in genotypes:
                if value(g[0]) == idx: inc(alt_count[i])
                if value(g[1]) == idx: inc(alt_count[i])
                inc(i)
            
            var key = join([vals[3], vals[2]], "\t")
            discard hasKeyOrPut(burden_table, key, newSeq[int32](vcf.n_samples))
            for i, val in alt_count:
                burden_table[key][i] += val
        inc(iter)
        if iter mod 10_000 == 0: write(stderr, ".")
    
    var header = "gene\timpact"
    for sample in vcf.samples:
        header.add("\t")
        header.add(sample)
    writeLine(stdout, header)

    for k, v in burden_table:
        writeLine(stdout, k, "\t", join(v, "\t"))

main()