Merge pull request #34 from gsteel/fix-exception-message

Fix missing space in exception message

src/Exception/SessionNotInitializedException.php

@@ -16,7 +16,7 @@ public static function forMissingRequestAttribute(): self
         return new self(
             sprintf(
                 'A session has not been initialized. Ensure that you pipe the %s middleware prior to'
-                . 'attempting to retrieve or use a session instance',
+                . ' attempting to retrieve or use a session instance.',
                 SessionMiddleware::class
             )
         );