made image generation exception safe

draw/code_to_image_wrapper.py

@@ -0,0 +1,13 @@
+import draw.code_to_image as cti
+
+class NSD_writer(object):
+    def __init__(self, filepath: str, x_sz: int, y_sz: int) -> None:
+        self.filepath = filepath
+        self.x_sz = x_sz
+        self.y_sz = y_sz
+    
+    def __enter__(self):
+        cti.NSD_init(self.x_sz, self.y_sz)
+    
+    def __exit__(self, _, __, ___):
+        cti.NSD_save(self.filepath)