Fixed exception while closing AtmCorr.logger.

Signed-off-by: Daniel Scheffler <danschef@gfz-potsdam.de>

HISTORY.rst

@@ -8,6 +8,7 @@ History
 * Fixed missing log messages regarding released locks.
 * Fixed issue #103 ('struct.error: unpack requires a buffer of 4 bytes' within SpatialIndexMediator in case of various
   parallel database accesses) by adding a database lock that blocks parallel database queries.
+* Fixed exception while closing AtmCorr.logger.
 
 
 0.18.11 (2020-11-03)

gms_preprocessing/algorithms/L1C_P.py

@@ -929,7 +929,8 @@ class AtmCorr(object):
 
         finally:
             # rs_image.logger must be closed properly in any case
-            rs_image.logger.close()
+            if rs_image.logger is not None:
+                rs_image.logger.close()
 
         # get processing infos
         self.proc_info = self.ac_input['options']['processing']