Fixed the error type to check

Author: Melissa LeBlanc-Williams

adafruit_featherwing/rtc_featherwing.py

@@ -34,8 +34,8 @@
 
 import time
 from collections import namedtuple
-import adafruit_ds3231
 from adafruit_featherwing import shared
+import adafruit_ds3231
 
 class RTCFeatherWing:
     """Class representing an `DS3231 Precision RTC FeatherWing
@@ -291,13 +291,13 @@ def unixtime(self):
         """
         try:
             return time.mktime(self._rtc.datetime)
-        except (ValueError, RuntimeError) as error:
+        except (AttributeError, RuntimeError) as error:
             print("Error attempting to run time.mktime() on this board\n", error)
 
     @unixtime.setter
     def unixtime(self, unixtime):
         if isinstance(unixtime, int):
             try:
                 self._rtc.datetime = time.localtime(unixtime)
-            except (ValueError, RuntimeError) as error:
+            except (AttributeError, RuntimeError) as error:
                 print("Error attempting to run time.localtime() on this board\n", error)