Exit with error if temp dir creation fails

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: cataphract

tests/lib.inc

@@ -5,7 +5,9 @@ function get_temp_dir() {
 	if (!$dir) {
 		$dir = sys_get_temp_dir() . DIRECTORY_SEPARATOR
 			. 'phpla_' . getmypid() . '_' . uniqid();
-		mkdir($dir, 0700);
+		if (!mkdir($dir, 0700)) {
+			exit("Could not create temp dir: $dir\n");
+		}
 
 		register_shutdown_function(function() use ($dir) {
 			$files = new RecursiveIteratorIterator(