Fix typing: use NoReturn

Author: Mauko Quiroga

.circleci/get-numpy-version.py

@@ -1,23 +1,34 @@
 #! /usr/bin/env python
 
+import os
 import sys
+import typing
 from packaging import version
+from typing import NoReturn, Union
 
 import numpy
 
+if typing.TYPE_CHECKING:
+    from packaging.version import LegacyVersion, Version
 
-def prev() -> str:
-    major, minor, _ = _installed().release
+
+def prev() -> NoReturn:
+    release = _installed().release
+
+    if release is None:
+        sys.exit(os.EX_DATAERR)
+
+    major, minor, _ = release
 
     if minor == 0:
-        exit(1)
+        sys.exit(os.EX_DATAERR)
 
     minor -= 1
     print(f"{major}.{minor}.0")  # noqa: T001
-    exit()
+    sys.exit(os.EX_OK)
 
 
-def _installed() -> version:
+def _installed() -> Union[LegacyVersion, Version]:
     return version.parse(numpy.__version__)