fix: remove unneeded warning with Medium2D and mode solver

Author: caseyflex

CHANGELOG.md

@@ -69,6 +69,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - More robust method for suppressing RF license warnings during tests.
 - Fixed frequency sampling of `TransmissionLineDataset` within `MicrowaveModeData` when using group index calculation.
 - Fixed DRC parsing for quoted categories in klayout plugin.
+- Removed mode solver warnings about evaluating permittivity of a `Medium2D`.
 
 ### Removed
 - Removed deprecated `use_complex_fields` parameter from `TwoPhotonAbsorption` and `KerrNonlinearity`. Parameters `beta` and `n2` are now real-valued only, as is `n0` if specified.

tidy3d/components/mode/mode_solver.py

@@ -1914,7 +1914,7 @@ def _is_tensorial(self) -> bool:
     def _intersecting_media(self) -> list:
         """List of media (including simulation background) intersecting the mode plane."""
         total_structures = [self.simulation.scene.background_structure]
-        total_structures += list(self.simulation.structures)
+        total_structures += list(self.simulation.volumetric_structures)
         return self.simulation.scene.intersecting_media(self.plane, total_structures)
 
     @cached_property