REVIEWED: `UnloadRenderTexture()`, additional check

src/rtextures.c

@@ -3793,8 +3793,11 @@ void UnloadRenderTexture(RenderTexture2D target)
 {
     if (target.id > 0)
     {
-        // Color texture attached to FBO is deleted
-        rlUnloadTexture(target.texture.id);
+        if (target.texture.id > 0)
+        {
+            // Color texture attached to FBO is deleted
+            rlUnloadTexture(target.texture.id);
+        }
 
         // NOTE: Depth texture/renderbuffer is automatically
         // queried and deleted before deleting framebuffer