Fix crash nav generation with impossibly-large grid

Author: s1lentq

regamedll/game_shared/bot/nav_area.cpp

@@ -1793,6 +1793,13 @@ void GenerateNavigationAreaMesh()
 			break;
 	}
 
+	if (!TheNavAreaList.size())
+	{
+		// If we somehow have no areas, don't try to create an impossibly-large grid
+		TheNavAreaGrid.Initialize(0, 0, 0, 0);
+		return;
+	}
+
 	Extent extent;
 	extent.lo.x = 9999999999.9f;
 	extent.lo.y = 9999999999.9f;
@@ -4674,6 +4681,12 @@ void CNavAreaGrid::Initialize(float minX, float maxX, float minY, float maxY)
 // Add an area to the grid
 void CNavAreaGrid::AddNavArea(CNavArea *area)
 {
+	if (!m_grid)
+	{
+		// If we somehow have no grid (manually creating a nav area without loading or generating a mesh), don't crash
+		TheNavAreaGrid.Initialize(0, 0, 0, 0);
+	}
+
 	// add to grid
 	const Extent *extent = area->GetExtent();
 

regamedll/game_shared/bot/nav_file.cpp

@@ -846,6 +846,11 @@ NavErrorType LoadNavigationMap()
 	unsigned int count;
 	result = navFile.Read(&count, sizeof(unsigned int));
 
+	if (count == 0)
+	{
+		return NAV_INVALID_FILE;
+	}
+
 	Extent extent;
 	extent.lo.x = 9999999999.9f;
 	extent.lo.y = 9999999999.9f;