Added check for author and author_email in setup.cfg, if they don't exist an error is raised.

Author: OCopping

src/dls_python3_skeleton/__main__.py

@@ -149,13 +149,22 @@ def new(args):
     )
 
 
+cfg_issue = """Missing parameter in setup.cfg. Expected format:
+[metadata]
+name = example
+author = Firstname Lastname
+author_email = [email protected]"""
+
+
 def existing(args):
     path: Path = args.path
 
     assert path.is_dir(), f"Expected {path} to be an existing directory"
     package = validate_package(args)
     conf = ConfigParser()
     conf.read(path / "setup.cfg")
+    assert "author" in conf["metadata"], cfg_issue
+    assert "author_email" in conf["metadata"], cfg_issue
     merge_skeleton(
         path=args.path,
         org=args.org,