Skip null parameters in validateParameter

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

src/Database/Concerns/ValidatesDatabaseParameters.php

@@ -59,12 +59,20 @@ trait ValidatesDatabaseParameters
         $allowlist = $allowlist ?? static::parameterAllowlist();
 
         foreach ((array) $parameters as $parameter) {
+            if (is_null($parameter)) {
+                continue;
+            }
+
             foreach (str_split($parameter) as $char) {
                 if (! str_contains($allowlist, $char)) {
                     throw new InvalidArgumentException("Invalid character '{$char}' in parameter: {$parameter}");
                 }
             }
         }
+                    throw new InvalidArgumentException("Invalid character '{$char}' in parameter: {$parameter}");
+                }
+            }
+        }
 
         return $parameters;
     }