Bug 36863: Deal with non-listed methods in CSRF plack middleware

Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>

Koha/Middleware/CSRF.pm

@@ -77,6 +77,9 @@ sub call {
             }
         }
     }
+    elsif ( !exists $stateless_methods{$request_method} && !exists $stateful_methods{$request_method} ) {
+        $error = sprintf "unknown or unsupported method %s", $request_method;
+    }
 
     if ($error) {