add texture_quad_batch assertion

src/textures.c

@@ -2,6 +2,7 @@
 #include <stb_image.h>
 #include <opengl.h>
 #include <stdio.h>
+#include <assert.h>
 
 RenderBatch* texture_quad_batch = NULL;
 int max_textures;
@@ -39,6 +40,7 @@ uint32_t load_texture(const char* path) {
 }
 
 void draw_texture(uint32_t id, vec3 pos, vec4 color) {
+    assert(texture_quad_batch != NULL && "texture_quad_batch is null, was setup_textures() called?");
     batch_draw_texture(texture_quad_batch, id, pos, color);
 }