Skip exception if model doesn't exist after delete failure

- bug: 2016
Change-Id: I9d118602c747840a4a32fd670c8724c82c1ee094
Signed-off-by: David Garcia <david.garcia@canonical.com>
diff --git a/n2vc/libjuju.py b/n2vc/libjuju.py
index 1fade62..bca3665 100644
--- a/n2vc/libjuju.py
+++ b/n2vc/libjuju.py
@@ -1341,6 +1341,10 @@
                 controller,
                 timeout=total_timeout,
             )
+        except Exception as e:
+            if not await self.model_exists(model_name, controller=controller):
+                return
+            raise e
         finally:
             if model:
                 await self.disconnect_model(model)