fix(ir): do not panic, if generating postfix for Any type

[tdakkota]

Prevent panic in boxing cases like "array of Any"

[codecov]

Codecov Report

Merging #187 (51ef729) into main (ef7463c) will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #187      +/-   ##
==========================================
+ Coverage   67.94%   68.01%   +0.06%     
==========================================
  Files          99       99              
  Lines        6274     6275       +1     
==========================================
+ Hits         4263     4268       +5     
+ Misses       1762     1759       -3     
+ Partials      249      248       -1     

Impacted Files	Coverage Δ
internal/ir/type.go	73.14% <100.00%> (+1.18%)	⬆️
gen/reduce.go	74.28% <0.00%> (+8.57%)	⬆️

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