Fix error when ctx is not defined on ClickExceptions

The error handling code for `ClickException` assumed that `ctx` is
defined for the exception object, which is true for many of the
subclasses, but not all.

Check for `ctx` before assuming it exists.

Author: dchiquito

djclick/adapter.py

@@ -71,7 +71,7 @@ def run_from_argv(self, argv):
             if exit_code:
                 sys.exit(exit_code)
         except click.ClickException as e:
-            if getattr(e.ctx, "traceback", False):  # NOCOV
+            if getattr(e, "ctx", False) and getattr(e.ctx, "traceback", False):  # NOCOV
                 raise
             e.show()
             sys.exit(e.exit_code)