Fixed #19257 -- Don't swallow command's KeyError in call_command

Thanks Giovanni Bajo for the report.

django/core/management/__init__.py

@@ -136,13 +136,14 @@ def call_command(name, *args, **options):
     # Load the command object.
     try:
         app_name = get_commands()[name]
+    except KeyError:
+        raise CommandError("Unknown command: %r" % name)
+
     if isinstance(app_name, BaseCommand):
         # If the command is already loaded, use it directly.
         klass = app_name
     else:
         klass = load_command_class(app_name, name)
-    except KeyError:
-        raise CommandError("Unknown command: %r" % name)
 
     # Grab out a list of defaults from the options. optparse does this for us
     # when the script runs from the command line, but since call_command can