fix: report background images that cannot be converted

A tensor that Pillow could not turn into an image raised out of the node
and failed the workflow. The documented console warning never ran.

nodes/ideogram4_nodes.py

@@ -210,7 +210,14 @@ def save_bg_image_to_temp(guid, image):
             exc, raw_guid,
         )
         return None
-    pil = _tensor_to_pil(image)
+    try:
+        pil = _tensor_to_pil(image)
+    except Exception as exc:
+        _bg_warn(
+            "background image was not saved: could not convert the image tensor (guid=%s): %s",
+            safe_guid, exc,
+        )
+        return None
     if pil is None:
         _bg_warn("background image was not saved: could not convert the image tensor (guid=%s)", safe_guid)
         return None

tests/test_nodes.py

@@ -2,6 +2,7 @@
 
 import json
 import unittest
+from unittest.mock import MagicMock, patch
 
 # conftest.py handles mocking and path setup
 from nodes.ideogram4_nodes import (
@@ -400,6 +401,16 @@ class TestPromptHelpers(unittest.TestCase):
         self.assertIsNone(result)
         self.assertTrue(any("invalid background guid" in line.lower() for line in cm.output))
 
+    def test_save_bg_image_warns_when_conversion_fails(self):
+        guid = "12345678-1234-4abc-8abc-123456789012"
+        image_mod = save_bg_image_to_temp.__globals__["Image"]
+        with patch.object(image_mod, "fromarray", side_effect=ValueError("bad shape")):
+            with self.assertLogs("byae.ideogram.bg", level="WARNING") as cm:
+                result = save_bg_image_to_temp(guid, MagicMock())
+        self.assertIsNone(result)
+        self.assertTrue(any("could not convert" in line.lower() for line in cm.output))
+        self.assertTrue(any("bad shape" in line for line in cm.output))
+
 
 class TestPromptAssembly(unittest.TestCase):
     """Test full prompt assembly logic without ComfyUI runtime."""