Avoid null pointer exception in the UIScaler

TLM/TLM/U/UIScaler.cs

@@ -5,11 +5,40 @@ namespace TrafficManager.U {
     using UnityEngine;
 
     public static class UIScaler {
+        public const float GUI_WIDTH = 1920f;
+        public const float GUI_HEIGHT = 1080f;
+
+        /// <summary>Caching because UIView.Instance.uiCamera can be null sometimes.</summary>
+        private static float cachedGuiWidth = GUI_WIDTH;
+
+        /// <summary>Caching because UIView.Instance.uiCamera can be null sometimes.</summary>
+        private static float cachedGuiHeight = GUI_HEIGHT;
+
         /// <summary>Screen width for GUI is always fixed at 1920.</summary>
-        public static float GuiWidth => Singleton<UIView>.instance.uiCamera.pixelWidth;
+        public static float GuiWidth {
+            // TODO: Double check if GUI never changes width, the code below can be a const
+            get {
+                UIView uiView = UIView.GetAView();
+                if (uiView != null) {
+                    UIScaler.cachedGuiWidth = uiView.uiCamera.pixelWidth;
+                }
+
+                return UIScaler.cachedGuiWidth;
+            }
+        }
 
         /// <summary>Screen height for GUI is always fixed at 1080.</summary>
-        public static float GuiHeight => Singleton<UIView>.instance.uiCamera.pixelHeight;
+        public static float GuiHeight {
+            // TODO: Double check if GUI never changes height, the code below can be a const
+            get {
+                UIView uiView = UIView.GetAView();
+                if (uiView != null) {
+                    UIScaler.cachedGuiHeight = uiView.uiCamera.pixelHeight;
+                }
+
+                return UIScaler.cachedGuiHeight;
+            }
+        }
 
         /// <summary>
         /// Calculate UI scale based on GUI scale slider in options multiplied by uiView's scale.
@@ -26,8 +55,8 @@ public static float GetScale() {
         /// <returns>GUI space position.</returns>
         internal static Vector2 ScreenPointToGuiPoint(Vector2 screenPos) {
             return new Vector2(
-                (screenPos.x * 1920f) / Screen.width,
-                (screenPos.y * 1080f) / Screen.height);
+                (screenPos.x * GUI_WIDTH) / Screen.width,
+                (screenPos.y * GUI_HEIGHT) / Screen.height);
         }
     }
 }

TLM/TLM/Util/GeometryUtil.cs

@@ -13,10 +13,13 @@ public static class GeometryUtil {
         /// <summary>Transforms a world point into a screen point.</summary>
         /// <param name="worldPos">Position in the world.</param>
         /// <param name="screenPos">2d position on screen.</param>
-        /// <returns>Screen point in pixels. Note: For use in UI transform to GUI coords.</returns>
+        /// <returns>
+        /// Screen point in pixels. Note: For use in UI transform to GUI coords
+        /// use <see cref="UIScaler.ScreenPointToGuiPoint"/>.
+        /// </returns>
         internal static bool WorldToScreenPoint(Vector3 worldPos, out Vector3 screenPos) {
             screenPos = Camera.main.WorldToScreenPoint(worldPos);
-            screenPos.y = UIScaler.GuiHeight - screenPos.y;
+            screenPos.y = Screen.height - screenPos.y;
 
             return screenPos.z >= 0;
         }