Return created dataset in write_compressed_frames

src/cal_tools/tools.py

@@ -951,3 +951,5 @@ def write_compressed_frames(
             # Each frame is 1 complete chunk
             chunk_start = (i,) + (0,) * (dataset.ndim - 1)
             dataset.id.write_direct_chunk(chunk_start, compressed)
+
+    return dataset