Fix remaining errors and enable strict mode (#1628)

## Description:

#1075 

Fixing all remaining type errors caused by strict mode and enable it.

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I have read and accepted the CLA agreement (only required once).

## Please put your Discord username so you can be contacted if a bug or
regression is found:

azlod

---------

Co-authored-by: Scott Anderson <662325+scottanderson@users.noreply.github.com>

src/core/execution/SAMLauncherExecution.ts

@@ -1,6 +1,7 @@
 import {
   Execution,
   Game,
+  isUnit,
   MessageType,
   Player,
   Unit,
@@ -80,7 +81,9 @@ class SAMTargetingSystem {
       [UnitType.AtomBomb, UnitType.HydrogenBomb],
       ({ unit }) => {
         return (
-          unit.owner() !== this.player && !this.player.isFriendly(unit.owner())
+          isUnit(unit) &&
+          unit.owner() !== this.player &&
+          !this.player.isFriendly(unit.owner())
         );
       },
     );
@@ -212,6 +215,7 @@ export class SAMLauncherExecution implements Execution {
       this.MIRVWarheadSearchRadius,
       UnitType.MIRVWarhead,
       ({ unit }) => {
+        if (!isUnit(unit)) return false;
         if (unit.owner() === this.player) return false;
         if (this.player.isFriendly(unit.owner())) return false;
         const dst = unit.targetTile();