Use ex-info for varity specific exception

[totakke]

ex-info is more useful for catch side in some cases such as debugging or dispatch.

[codecov]

Codecov Report

Merging #20 into master will decrease coverage by 0.01%.
The diff coverage is 28.57%.

@@            Coverage Diff             @@
##           master      #20      +/-   ##
==========================================
- Coverage      39%   38.99%   -0.02%     
==========================================
  Files          13       13              
  Lines        1446     1467      +21     
  Branches       31       31              
==========================================
+ Hits          564      572       +8     
- Misses        851      864      +13     
  Partials       31       31

Impacted Files	Coverage Δ
src/varity/vcf_to_hgvs/protein.clj	28.57% <0%> (ø)	⬆️
src/varity/hgvs_to_vcf/protein.clj	10.14% <0%> (ø)	⬆️
src/varity/vcf_to_hgvs/cdna.clj	26.36% <0%> (ø)	⬆️
src/varity/vcf_to_hgvs.clj	15.09% <0%> (-1.24%)	⬇️
src/varity/hgvs_to_vcf.clj	25.42% <0%> (-0.44%)	⬇️
src/varity/vcf_to_hgvs/common.clj	66.88% <90.9%> (+1.81%)	⬆️

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[federkasten]

LGTM 🙆‍♂️ This changes are helpful for me too.