fix: handle non-sketch inputs

app.py

@@ -304,6 +304,9 @@ def get_color(n):
 def create_mixed_img(current, state, w=512, h=512):
     w, h = int(w), int(h)
     image_np = np.full([h, w, 4], 255)
+    if state is None:
+        state = {}
+
     colors = get_color(len(state))
     idx = 0