Fix potential NPE when clicking 'ctrl+A' to add units to battle calc

[DanVanAtta]

Clicking around on map with 'ctrl+A' can encounter a NPE due
to null 'current territory'

Testing

Screens Shots

Additional Notes to Reviewer

Release Note

FIX|Fix potential NullPointerException message when pressing 'ctrl+a' to add units to battle calculator

[codecov]

Codecov Report

Merging #8276 (fda2bf4) into master (a7a7576) will increase coverage by 0.00%.
The diff coverage is 0.00%.

@@            Coverage Diff            @@
##             master    #8276   +/-   ##
=========================================
  Coverage     24.83%   24.84%           
+ Complexity     7304     7303    -1     
=========================================
  Files          1265     1265           
  Lines         79592    79565   -27     
  Branches      11085    11075   -10     
=========================================
- Hits          19765    19764    -1     
+ Misses        57754    57727   -27     
- Partials       2073     2074    +1     

Impacted Files	Coverage Δ	Complexity Δ
...ategy/triplea/ai/pro/data/ProTerritoryManager.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...riplea/odds/calculator/BattleCalculatorDialog.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...egy/triplea/ui/PlacementUnitsCollapsiblePanel.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...trategy/triplea/ui/unit/scroller/UnitScroller.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
.../java/games/strategy/triplea/delegate/Matches.java	45.03% <0.00%> (-0.11%)	374.00% <0.00%> (-1.00%)

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