Prevent double allocations of memory block for quakeparms, and report if allocation of hunk memory fails.

Assets/Scripts/QuakeParms.cs

@@ -29,7 +29,9 @@ public class QuakeParms
 
     public IntPtr ToNativePtr()
     {
-        nativeBlock = Marshal.AllocHGlobal(Marshal.SizeOf<QuakeParms>());
+        if (nativeBlock == IntPtr.Zero)
+            nativeBlock = Marshal.AllocHGlobal(Marshal.SizeOf<QuakeParms>());
+        
         Marshal.StructureToPtr(this, nativeBlock, false);
         return nativeBlock;
     }
@@ -48,6 +50,10 @@ public class QuakeParms
     {
         memSize = memorySize;
         memBase = Marshal.AllocHGlobal(memorySize);
+        if (memBase == IntPtr.Zero)
+        {
+            throw new OutOfMemoryException($"Could not allocate {memorySize / 1024 / 1024} MB of heap memory!");
+        }
     }
         
     public void Destroy()