deactivate_realm: Improve error handling for unknown realm.

zerver/management/commands/deactivate_realm.py

@@ -3,6 +3,8 @@ from __future__ import print_function
 
 from django.core.management.base import BaseCommand
 
+import sys
+
 from zerver.lib.actions import do_deactivate_realm
 from zerver.models import get_realm
 
@@ -14,6 +16,10 @@ class Command(BaseCommand):
                             help='domain of realm to deactivate')
 
     def handle(self, *args, **options):
+        realm = get_realm(options["domain"])
+        if realm is None:
+            print("Could not find realm %s" % (options["domain"],))
+            sys.exit(1)
         print("Deactivating", options["domain"])
-        do_deactivate_realm(get_realm(options["domain"]))
+        do_deactivate_realm(realm)
         print("Done!")