Avoid syntax warnings when IO is not loaded

[wilfwilson]

This is a hack to resolve #23; perhaps @fingolfin or someone else has a nicer solution?

[codecov]

Codecov Report

❌ Patch coverage is 71.42857% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 55.48%. Comparing base (3b63b4b) to head (5ac62ce).
⚠️ Report is 6 commits behind head on master.

Files with missing lines	Patch %	Lines
lib/serre.gi	71.42%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #24      +/-   ##
==========================================
+ Coverage   55.07%   55.48%   +0.41%     
==========================================
  Files          25       25              
  Lines        1380     1386       +6     
==========================================
+ Hits          760      769       +9     
+ Misses        620      617       -3     

Files with missing lines	Coverage Δ
lib/serre.gi	81.77% <71.42%> (+1.86%)	⬆️

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[fingolfin]

This line could be removed now (and then the else/fi as well of course)

[fingolfin]

I've applied the changes I suggested and did some more cleanup.

[wilfwilson]

Nice simplification.

[dimpase]

Thanks for working on this. For some reason I don't get notifications for this repo emailed to me.