feat: protect against non 3D data

src/cryo_et_neuroglancer/segmentation_encoding.py

@@ -213,6 +213,8 @@ def create_segmentation_chunk(
 ) -> Chunk:
     """Convert data in a dask array to a neuroglancer segmentation chunk"""
     bz, by, bx = block_size
+    if len(data.shape) != 3:
+        raise ValueError("Data must be 3-dimensional")
     gz, gy, gx = get_grid_size_from_block_shape(data.shape, block_size)
     stored_lookup_tables: dict[bytes, tuple[int, int]] = {}
     # big enough to hold the 64-bit starting block headers

src/cryo_et_neuroglancer/write_segmentation.py

@@ -90,6 +90,8 @@ def main(
     for c in create_segmentation(dask_data, block_size):
         c.write_to_directory(output_directory / data_directory)
 
+    if len(dask_data.chunksize) != 3:
+        raise ValueError(f"Expected 3 chunk dimensions, got {len(dask_data.chunksize)}")
     metadata = _create_metadata(
         dask_data.chunksize, block_size, dask_data.shape, data_directory, resolution
     )