Only perform activity actions when activity is running

When game starts, there is no activity running yet, but when loading
data through `g_PresetMan.LoadAllDataModules()` call in `main()`, this
will get executed and call a member function on a nullptr.

Author: janisozaur

Source/Managers/MovableMan.cpp

@@ -683,7 +683,9 @@ void MovableMan::AddActor(Actor* actorToAdd) {
 
 void MovableMan::AddItem(HeldDevice* itemToAdd) {
 	if (itemToAdd) {
-		g_ActivityMan.GetActivity()->ForceSetTeamAsActive(itemToAdd->GetTeam());
+		if (g_ActivityMan.ActivityRunning()) {
+			g_ActivityMan.GetActivity()->ForceSetTeamAsActive(itemToAdd->GetTeam());
+		}
 		itemToAdd->SetAsAddedToMovableMan();
 		itemToAdd->CorrectAttachableAndWoundPositionsAndRotations();
 
@@ -706,7 +708,9 @@ void MovableMan::AddItem(HeldDevice* itemToAdd) {
 
 void MovableMan::AddParticle(MovableObject* particleToAdd) {
 	if (particleToAdd) {
-		g_ActivityMan.GetActivity()->ForceSetTeamAsActive(particleToAdd->GetTeam());
+		if (g_ActivityMan.ActivityRunning()) {
+			g_ActivityMan.GetActivity()->ForceSetTeamAsActive(particleToAdd->GetTeam());
+		}
 		particleToAdd->SetAsAddedToMovableMan();
 		if (MOSRotating* particleToAddAsMOSRotating = dynamic_cast<MOSRotating*>(particleToAdd)) {
 			particleToAddAsMOSRotating->CorrectAttachableAndWoundPositionsAndRotations();