No need to check for $cdn existance

[DarkSide666]

• no need to check for $cdn == false here. isset() will do the same.
• add some comments

[codecov]

Codecov Report

Merging #244 into develop will not change coverage.
The diff coverage is 100%.

@@            Coverage Diff            @@
##             develop    #244   +/-   ##
=========================================
  Coverage       73.7%   73.7%           
+ Complexity      1051    1046    -5     
=========================================
  Files             58      58           
  Lines           2514    2514           
=========================================
  Hits            1853    1853           
  Misses           661     661

Impacted Files	Coverage Δ	Complexity Δ
src/App.php	75.55% <100%> (ø)	93 <0> (-5)	⬇️

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