Update neo/rawio/edfrawio.py

Co-authored-by: Zach McKenzie <92116279+zm711@users.noreply.github.com>

Author: h-mayorquin

neo/rawio/edfrawio.py

@@ -224,7 +224,7 @@ def _get_analogsignal_chunk(self, block_index, seg_index, i_start, i_stop, strea
 
         # load data into numpy array buffer
         data = []
-        self._open()
+        self._open_reader()
         for i, channel_idx in enumerate(selected_channel_idxs):
             # use int32 for compatibility with pyedflib
             buffer = np.empty(n, dtype=np.int32)