Fix validation for array elements

[MrCrayon]

Fixes validation when array does not contain files, ex. belongsToMany relationship.

Symfony\Component\Debug\Exception\FatalThrowableError
Call to a member function getClientOriginalName() on string

[codecov]

Codecov Report

Merging #4922 into 1.4 will decrease coverage by 0.00%.
The diff coverage is 66.66%.

@@             Coverage Diff              @@
##                1.4    #4922      +/-   ##
============================================
- Coverage     62.97%   62.96%   -0.01%     
- Complexity     1373     1374       +1     
============================================
  Files           194      194              
  Lines          4005     4007       +2     
============================================
+ Hits           2522     2523       +1     
- Misses         1483     1484       +1     

Impacted Files	Coverage Δ	Complexity Δ
src/Http/Controllers/Controller.php	80.85% <66.66%> (-0.45%)	77.00 <0.00> (+1.00)	⬇️

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[EduCavalheiro]

Tested, it works well.