Unload functions clear object to 0 so they would not be ready in Is*Ready.

src/textures.c

@@ -188,6 +188,7 @@ int ltextureUnloadImage( lua_State* L ) {
 	Image* image = uluaGetImage( L, 1 );
 
 	UnloadImage( *image );
+	memset( image, 0, sizeof( Image ) );
 
 	return 0;
 }
@@ -1296,6 +1297,7 @@ int ltextureUnloadTexture( lua_State* L ) {
 	Texture* texture = uluaGetTexture( L, 1 );
 
 	UnloadTexture( *texture );
+	memset( texture, 0, sizeof( Texture ) );
 
 	return 0;
 }
@@ -1324,6 +1326,7 @@ int ltextureUnloadRenderTexture( lua_State* L ) {
 	RenderTexture* target = uluaGetRenderTexture( L, 1 );
 
 	UnloadRenderTexture( *target );
+	memset( target, 0, sizeof( RenderTexture ) );
 
 	return 0;
 }