Update DefinitionResolver.php

[Sensirex]

from issue
#326

[codecov]

Codecov Report

Merging #333 into master will not change coverage.
The diff coverage is 0%.

@@            Coverage Diff            @@
##             master     #333   +/-   ##
=========================================
  Coverage     84.15%   84.15%           
- Complexity      811      812    +1     
=========================================
  Files            59       59           
  Lines          1717     1717           
=========================================
  Hits           1445     1445           
  Misses          272      272

Impacted Files	Coverage Δ	Complexity Δ
src/DefinitionResolver.php	81.73% <0%> (ø)	276 <0> (+1)	✅

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[felixfbecker]

As I already said before, this is not the fix. The bug is that type gets set to null, not that a null value isn't handled.