this derivation will be built:
  /nix/store/ymhc867q0ds35xzpjzjlbdyhplq2dnxz-spec-jsonfmt.drv
building '/nix/store/ymhc867q0ds35xzpjzjlbdyhplq2dnxz-spec-jsonfmt.drv'
spec-jsonfmt> Error: failed to format json file: invalid/a.json: invalid character ',' looking for beginning of object key string
spec-jsonfmt> Error: failed to format json file: invalid/a.json: invalid character ',' looking for beginning of object key string

upload niks3: ok