Fix missing assemblies, add ifdef for UNITY_EDITOR

Editor scripts require ifdef UNITY_EDITOR so as to not be compiled

Assets/Scripts/Assignment/Assignment.cs

@@ -1,6 +1,6 @@
 using System;
 using System.Collections.Generic;
-using System.Collections.Immutable;
+using System.Collections;
 using UnityEngine;
 using System.Linq;
 using System.Diagnostics.Contracts;

Assets/Scripts/Editor/GenerateCone.cs

@@ -3,6 +3,7 @@ using UnityEditor;
 using System;
 using System.Collections.Generic;
 
+#if UNITY_EDITOR
 public class GenerateCone : EditorWindow {
   private int sides = 16;
   private float baseRadius = 1f;
@@ -139,4 +140,5 @@ public class GenerateCone : EditorWindow {
     }
     return sum / vertices.Count;
   }
-}
+}
+#endif

Assets/Scripts/MicromissileAssembly.asmdef

@@ -2,7 +2,8 @@
     "name": "MicromissileAssembly",
     "rootNamespace": "",
     "references": [
-        "GUID:6055be8ebefd69e48b49212b09b47b2f"
+        "GUID:6055be8ebefd69e48b49212b09b47b2f",
+        "GUID:c668b7a00ffe56a498ddb1fc9f96f4e6"
     ],
     "includePlatforms": [],
     "excludePlatforms": [],