Remove throw in the catch block

The throw statement in the catch won't be handled because
there is no higher level or top level error handler

Change-Id: I581a2a55747a97a04ac10c9befedc81f055c3ef6
diff --git a/client/src/pages/Registration.tsx b/client/src/pages/Registration.tsx
index acbf8f9..50686f5 100644
--- a/client/src/pages/Registration.tsx
+++ b/client/src/pages/Registration.tsx
@@ -89,7 +89,7 @@
       } else if (e instanceof InvalidPassword) {
         setErrorAlertContent(t('login_invalid_password'));
       } else {
-        throw e;
+        setErrorAlertContent(t('unknown_error_alert'));
       }
     }
   };
@@ -108,7 +108,7 @@
       } else if (e instanceof InvalidCredentials) {
         setErrorAlertContent(t('login_invalid_credentials'));
       } else {
-        throw e;
+        setErrorAlertContent(t('unknown_error_alert'));
       }
     }
   };