Handle empty EUI64 manufacturing tokens (#570)

bellows/ezsp/__init__.py

@@ -397,6 +397,11 @@ async def _get_nv3_restored_eui64_key(self) -> t.NV3KeyId | None:
     async def _get_mfg_custom_eui_64(self) -> t.EmberEUI64 | None:
         """Get the custom EUI 64 manufacturing token, if it has a valid value."""
         (data,) = await self.getMfgToken(t.EzspMfgTokenId.MFG_CUSTOM_EUI_64)
+
+        # Manufacturing tokens do not exist in RCP firmware: all reads are empty
+        if not data:
+            raise EzspError("Firmware does not support MFG_CUSTOM_EUI_64 token")
+
         mfg_custom_eui64, _ = t.EmberEUI64.deserialize(data)
 
         if mfg_custom_eui64 == t.EmberEUI64.convert("FF:FF:FF:FF:FF:FF:FF:FF"):
@@ -406,7 +411,10 @@ async def _get_mfg_custom_eui_64(self) -> t.EmberEUI64 | None:
 
     async def can_burn_userdata_custom_eui64(self) -> bool:
         """Checks if the device EUI64 can be burned into USERDATA."""
-        return await self._get_mfg_custom_eui_64() is None
+        try:
+            return await self._get_mfg_custom_eui_64() is None
+        except EzspError:
+            return False
 
     async def can_rewrite_custom_eui64(self) -> bool:
         """Checks if the device EUI64 can be written any number of times."""

tests/test_ezsp.py

@@ -504,7 +504,7 @@ async def _mock_cmd(*args, **kwargs):
 
 @pytest.mark.parametrize(
     "value, expected_result",
-    [(b"\xFF" * 8, True), (bytes.fromhex("0846b8a11c004b1200"), False)],
+    [(b"\xFF" * 8, True), (bytes.fromhex("0846b8a11c004b1200"), False), (b"", False)],
 )
 async def test_can_burn_userdata_custom_eui64(ezsp_f, value, expected_result):
     """Test detecting if a custom EUI64 has been written."""