Refactor/update error msg

[fubuloubu]

What I did

Fixes #2159

How I did it

Grep foo

Cute Animal Picture

[codecov-commenter]

Codecov Report

Merging #2160 into master will decrease coverage by 0.01%.
The diff coverage is 25.00%.

@@            Coverage Diff             @@
##           master    #2160      +/-   ##
==========================================
- Coverage   84.95%   84.94%   -0.02%     
==========================================
  Files          83       83              
  Lines        8333     8334       +1     
  Branches     2012     2013       +1     
==========================================
  Hits         7079     7079              
- Misses        752      753       +1     
  Partials      502      502              

Impacted Files	Coverage Δ
vyper/types/types.py	82.50% <25.00%> (-0.42%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update c173ba7...ab24a26. Read the comment docs.