Fix NPE in ArrayAgg extractFinalResult functions

[xiangfu0]

Fix NPE issue reported in #13343 to extract final result.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 12 lines in your changes missing coverage. Please review.

Project coverage is 62.11%. Comparing base (59551e4) to head (bc26fa1).
Report is 608 commits behind head on master.

Files	Patch %	Lines
...ion/function/array/BaseArrayAggDoubleFunction.java	0.00%	1 Missing and 1 partial ⚠️
...tion/function/array/BaseArrayAggFloatFunction.java	0.00%	1 Missing and 1 partial ⚠️
...gation/function/array/BaseArrayAggIntFunction.java	0.00%	1 Missing and 1 partial ⚠️
...ation/function/array/BaseArrayAggLongFunction.java	0.00%	1 Missing and 1 partial ⚠️
...ion/function/array/BaseArrayAggStringFunction.java	0.00%	1 Missing and 1 partial ⚠️
...ry/aggregation/function/array/ListAggFunction.java	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #13358      +/-   ##
============================================
+ Coverage     61.75%   62.11%   +0.35%     
+ Complexity      207      198       -9     
============================================
  Files          2436     2548     +112     
  Lines        133233   139966    +6733     
  Branches      20636    21729    +1093     
============================================
+ Hits          82274    86935    +4661     
- Misses        44911    46438    +1527     
- Partials       6048     6593     +545     

Flag	Coverage Δ
custom-integration1	<0.01% <0.00%> (-0.01%)	⬇️
integration	<0.01% <0.00%> (-0.01%)	⬇️
integration1	<0.01% <0.00%> (-0.01%)	⬇️
integration2	0.00% <0.00%> (ø)
java-11	62.07% <0.00%> (+0.36%)	⬆️
java-21	61.98% <0.00%> (+0.35%)	⬆️
skip-bytebuffers-false	62.09% <0.00%> (+0.35%)	⬆️
skip-bytebuffers-true	61.95% <0.00%> (+34.22%)	⬆️
temurin	62.11% <0.00%> (+0.35%)	⬆️
unittests	62.10% <0.00%> (+0.35%)	⬆️
unittests1	46.69% <0.00%> (-0.20%)	⬇️
unittests2	27.71% <0.00%> (-0.02%)	⬇️

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