Fix loading an extra element when not necessary

[Baptouuuu]

Problem

When using a lazy Sequence with a take call it would load an extra element from the generator that is never used.

In most cases this is not very problematic.

But working on Innmind/io#1 it causes problems as it ends up trying to load a value from a stream that is no longer readable and ends up with an error.

Solution

• Add a pre-condition if the size is 0
• Stop the generator before loading the next value

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.80%. Comparing base (6f6ca72) to head (76fa470).
Report is 3 commits behind head on develop.

Additional details and impacted files

@@              Coverage Diff              @@
##             develop      #39      +/-   ##
=============================================
- Coverage      97.91%   97.80%   -0.11%     
- Complexity      1049     1050       +1     
=============================================
  Files             72       72              
  Lines           4216     4235      +19     
=============================================
+ Hits            4128     4142      +14     
- Misses            88       93       +5     

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