ref readonly modifiers for GetByteAt & indexer, add IsDisposed check to GetByteAt for MutableScript

Author: GreemDev

src/Lib/Internal/ExecutableScript.cs

@@ -8,10 +8,9 @@ public abstract class ExecutableScript : IDisposable
 
     public abstract void Dispose();
 
-    protected virtual byte GetByteAt(int idx) => Code[idx];
-
-    public byte this[int idx] => GetByteAt(idx);
+    protected virtual ref readonly byte GetByteAt(int idx) => ref Code[idx];
 
+    public ref readonly byte this[int idx] => ref GetByteAt(idx);
 
     public bool IsDisposed { get; protected set; }
 

src/Lib/Internal/MutableScript.cs

@@ -15,6 +15,14 @@ public class MutableScript : ExecutableScript
 
     public override ReadOnlySpan<byte> Code => CodeBuffer.RoSpan;
 
+    protected override ref readonly byte GetByteAt(int idx)
+    {
+        if (IsDisposed)
+            throw new ObjectDisposedException(nameof(MutableScript), "Cannot access bytecode of a disposed Script.");
+
+        return ref CodeBuffer[idx];
+    }
+
     public Script MoveToImmutable()
     {
         // Trim the excess (null) bytes before copying
@@ -112,7 +120,7 @@ public void PatchJump(int offset)
     }
 
     #endregion
-    
+
     public override void Dispose()
     {
         if (IsDisposed)

src/Lib/Public/Entities/Script.cs

@@ -17,12 +17,12 @@ public Script(byte[] codeBuffer, Value[] constants)
         _constants = constants;
     }
 
-    protected override byte GetByteAt(int idx)
+    protected override ref readonly byte GetByteAt(int idx)
     {
         if (IsDisposed)
             throw new ObjectDisposedException(nameof(Script), "Cannot access bytecode of a disposed Script.");
 
-        return _code[idx];
+        return ref _code[idx];
     }
 
     public override void Dispose()