Added error logging for unexpected exceptions.

- Thanks to Tod Olson!

module/VuFind/src/VuFind/Auth/Manager.php

@@ -463,7 +463,12 @@ class Manager implements ServiceLocatorAwareInterface
             // Pass password security exceptions through unmodified
             throw $e;
         } catch (\Exception $e) {
-            // Catch other exceptions and treat them as technical difficulties
+            // Catch other exceptions, log verbosely, and treat them as technical
+            // difficulties
+            error_log(
+                "Exception in " . get_class($this) . "::login: " . $e->getMessage()
+            );
+            error_log($e);
             throw new AuthException('authentication_error_technical');
         }