Remove unnessary null checks

[axunonb]

Remove null checks having "Expression is always true or false according to NRT annotations" from Code Inspector.
Again, increasing coverage.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

Attention: Patch coverage is 42.10526% with 11 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
Ical.Net/Collections/GroupedListEnumerator.cs	50%	0 Missing and 2 partials ⚠️
...et/Serialization/DataTypes/PeriodListSerializer.cs	0%	0 Missing and 2 partials ⚠️
...al.Net/Serialization/DataTypes/PeriodSerializer.cs	0%	0 Missing and 2 partials ⚠️
...l.Net/Collections/Proxies/GroupedValueListProxy.cs	50%	1 Missing ⚠️
Ical.Net/Evaluation/RecurringEvaluator.cs	80%	0 Missing and 1 partial ⚠️
Ical.Net/Serialization/ComponentSerializer.cs	0%	0 Missing and 1 partial ⚠️
...alization/DataTypes/RecurrencePatternSerializer.cs	0%	0 Missing and 1 partial ⚠️
...Serialization/DataTypes/RequestStatusSerializer.cs	0%	0 Missing and 1 partial ⚠️

❌ Your patch status has failed because the patch coverage (42%) is below the target coverage (80%). You can increase the patch coverage or adjust the target coverage.
❌ Your project status has failed because the head coverage (67%) is below the target coverage (80%). You can increase the head coverage or adjust the target coverage.

@@         Coverage Diff         @@
##           main   #790   +/-   ##
===================================
  Coverage    66%    67%           
===================================
  Files       106    106           
  Lines      4464   4445   -19     
  Branches   1076   1071    -5     
===================================
- Hits       2962   2960    -2     
+ Misses     1057   1046   -11     
+ Partials    445    439    -6     

Files with missing lines	Coverage Δ
Ical.Net/Serialization/DataMapSerializer.cs	0% <ø> (ø)
...et/Serialization/DataTypes/AttachmentSerializer.cs	74% <100%> (+2%)	⬆️
...l.Net/Serialization/DataTypes/TriggerSerializer.cs	34% <ø> (+3%)	⬆️
Ical.Net/Serialization/SerializationUtil.cs	93% <ø> (+6%)	⬆️
...l.Net/Collections/Proxies/GroupedValueListProxy.cs	40% <50%> (-1%)	⬇️
Ical.Net/Evaluation/RecurringEvaluator.cs	97% <80%> (+3%)	⬆️
Ical.Net/Serialization/ComponentSerializer.cs	52% <0%> (ø)
...alization/DataTypes/RecurrencePatternSerializer.cs	93% <0%> (ø)
...Serialization/DataTypes/RequestStatusSerializer.cs	40% <0%> (+3%)	⬆️
Ical.Net/Collections/GroupedListEnumerator.cs	81% <50%> (ø)
... and 2 more

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[minichma]

Nice to see, how NRT helps improving the code.