prevent out of bounds array access

[NickAragua]

For aerospace/space scenarios the terrain type is out of bounds of the array above the changed code. We don't actually want to change the terrain type, but we want to avoid array out of bounds exceptions. This would manifest in aerospace scenarios failing to appear on the stratcon map.

[codecov]

Codecov Report

Merging #2849 (db0c43b) into master (616cfdb) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##             master    #2849      +/-   ##
============================================
- Coverage     10.64%   10.63%   -0.01%     
+ Complexity     3886     3879       -7     
============================================
  Files           721      721              
  Lines        100547   100550       +3     
  Branches      16413    16414       +1     
============================================
- Hits          10699    10691       -8     
- Misses        88469    88476       +7     
- Partials       1379     1383       +4     

Impacted Files	Coverage Δ
MekHQ/src/mekhq/campaign/mission/AtBScenario.java	0.00% <0.00%> (ø)
...ekhq/campaign/universe/RandomFactionGenerator.java	56.17% <0.00%> (-2.40%)	⬇️
MekHQ/src/mekhq/campaign/universe/Faction.java	64.74% <0.00%> (-1.93%)	⬇️
...ekHQ/src/mekhq/campaign/market/ContractMarket.java	59.80% <0.00%> (+0.19%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 616cfdb...db0c43b. Read the comment docs.