Fix maxwell gain_uV when lsb is not in settings

Author: alejoe91

neo/rawio/maxwellrawio.py

@@ -100,7 +100,15 @@ def _parse_header(self):
             elif int(version) > 20160704:
                 settings = h5['wells'][stream_id][self.rec_name]['settings']
                 sr = settings['sampling'][:][0]
-                gain_uV = settings['lsb'][:][0] * 1e6
+                if 'lsb' in settings:
+                    gain_uV = settings['lsb'][:][0] * 1e6
+                else:
+                    if "gain" not in settings:
+                        print("'gain' amd 'lsb' not found in settings. Setting gain to 512 (default)")
+                        gain = 512
+                    else:
+                        gain = settings['gain'][:][0]
+                    gain_uV = 3.3 / (1024 * gain) * 1e6
                 mapping = settings['mapping']
                 sigs = h5['wells'][stream_id][self.rec_name]['groups']['routed']['raw']