Fix integer power

[ichiban]

#201

[codecov-commenter]

Codecov Report

Merging #215 (b519b02) into main (6dd7811) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #215      +/-   ##
==========================================
+ Coverage   96.85%   96.86%   +0.01%     
==========================================
  Files          21       21              
  Lines        6288     6320      +32     
==========================================
+ Hits         6090     6122      +32     
  Misses        163      163              
  Partials       35       35              

Impacted Files	Coverage Δ
engine/integer.go	96.15% <100.00%> (+0.32%)	⬆️
engine/number.go	100.00% <100.00%> (ø)

---

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 6dd7811...b519b02. Read the comment docs.