output buffering handlers return string

Author: dg

src/Bridges/ApplicationLatte/SnippetRuntime.php

@@ -56,7 +56,7 @@ public function enter(string $name, string $type): void
 			($this->nestingLevel === 0 && $this->control->isControlInvalid($name))
 			|| ($type === self::TypeDynamic && ($previous = end($this->stack)) && $previous[1] === true)
 		) {
-			ob_start(fn() => null);
+			ob_start(fn() => '');
 			$this->nestingLevel = $type === self::TypeArea ? 0 : 1;
 			$obStarted = true;
 		} elseif ($this->nestingLevel > 0) {