fix: move key access inside falsy check

Otherwise, this fails when trying to create a new image.

Signed-off-by: Ralph Bean <[email protected]>

pyxis/create_container_image.py

@@ -370,9 +370,9 @@ def main():  # pragma: no cover
 
     # First check if it exists at all
     image = image_already_exists(args, args.architecture_digest, repository=None)
-    identifier = image["_id"]
     if image:
         # Then, check if it exists in association with the given repository
+        identifier = image["_id"]
         if image_already_exists(args, args.architecture_digest, repository=args.name):
             LOGGER.info(
                 f"Image with given docker_image_digest already exists as {identifier} "