fix text fields and exists operator

src/Record/Record.php

@@ -26,10 +26,10 @@ class Record implements JsonSerializable
 
         return trim(Str::lower(collect($arrObject)
             ->map(function($value){
-                if(!is_string($value)){
+                if(is_array($value)){
                     return $this->indexValues($value ?? []);
                 }
-                return $value;
+                return (string)$value;
             })
             ->values()->join(" ")." ". $this->_file?->originalName ?? ""));
     }