Add prettier message when syncing inexistent pair

vdirsyncer/cli/config.py

@@ -217,7 +217,10 @@ class Config(object):
             return expand_fetch_params(args)
 
     def get_pair(self, pair_name):
-        return PairConfig(self, pair_name, *self.pairs[pair_name])
+        try:
+            return PairConfig(self, pair_name, *self.pairs[pair_name])
+        except KeyError as e:
+            raise exceptions.PairNotFound(e, pair_name=pair_name)
 
 
 class PairConfig(object):

vdirsyncer/cli/utils.py

@@ -68,6 +68,7 @@ class JobFailed(RuntimeError):
     pass
 
 
+# TODO: Making this a decorator would be nice
 def handle_cli_error(status_name=None):
     '''
     Print a useful error message for the current exception.
@@ -118,6 +119,12 @@ def handle_cli_error(status_name=None):
         )
     except (click.Abort, KeyboardInterrupt, JobFailed):
         pass
+    except exceptions.PairNotFound as e:
+        cli_logger.error(
+            'Pair {pair_name} does not exist. Please check your '
+            'configuration file and make sure you\'ve typed the pair name '
+            'correctly'.format(pair_name=e.pair_name)
+        )
     except Exception as e:
         if status_name:
             msg = 'Unhandled exception occured for {}.'.format(

vdirsyncer/exceptions.py

@@ -35,6 +35,12 @@ class CollectionNotFound(Error):
     '''Collection not found'''
 
 
+class PairNotFound(Error):
+    '''Pair not found'''
+
+    pair_name = None
+
+
 class PreconditionFailed(Error):
     '''
       - The item doesn't exist although it should