If a taxonomy doesnt exists, fail early. Closes #1009

Author: jasonvarga

src/Stache/Repositories/TermRepository.php

@@ -62,6 +62,10 @@ public function findByUri(string $uri, string $site = null): ?Term
             return null;
         }
 
+        if (! Taxonomy::handleExists($taxonomy)) {
+            return null;
+        }
+
         $term = $this->query()
             ->where('slug', $slug)
             ->where('taxonomy', $taxonomy)