Null pointer exception when reading a complex type with empty arrays.…

[mregen]

… (#2798)

The server under test has a extension object with a complex type. Type id = {nsu=http://opcfoundation.org/UA/Machinery/Result/;i=5008}. This contains something with a variant array that is null though (-1). SetProperty should support setting a Array that is null. Therefore, test for null collection (case when length was encoded as -1) before dereferencing ahead of the ToArrray() conversion to Array.

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 25 lines in your changes missing coverage. Please review.

Project coverage is 54.69%. Comparing base (6ca0b1a) to head (c2b11cb).
Report is 1 commits behind head on release/1.5.374.

Files with missing lines	Patch %	Lines
Stack/Opc.Ua.Core/Types/Encoders/BinaryDecoder.cs	0.00%	0 Missing and 25 partials ⚠️

Additional details and impacted files

@@                 Coverage Diff                 @@
##           release/1.5.374    #2799      +/-   ##
===================================================
- Coverage            54.73%   54.69%   -0.04%     
===================================================
  Files                  349      349              
  Lines                65982    65982              
  Branches             13536    13561      +25     
===================================================
- Hits                 36118    36092      -26     
  Misses               25944    25944              
- Partials              3920     3946      +26     

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