Raise import error and add appropriate message

Bug: T353387
Change-Id: I93d1c8ce96e37a25973b35ddfd3767226d82fe68
---
M pywikibot/comms/http.py
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/pywikibot/comms/http.py b/pywikibot/comms/http.py
index 44447e2..65f1333 100644
--- a/pywikibot/comms/http.py
+++ b/pywikibot/comms/http.py
@@ -433,9 +433,8 @@
     auth = get_authentication(uri)
     if auth is not None and len(auth) == 4:
         if isinstance(requests_oauthlib, ImportError):
-            warn(str(requests_oauthlib), ImportWarning)
-            error(f'OAuth authentication not supported: {requests_oauthlib}')
-            auth = None
+            pywikibot.error(requests_oauthlib)
+            sys.exit(1)
         else:
             auth = requests_oauthlib.OAuth1(*auth)
 

