Fix code review feedback: correct time_to_first_byte calculation and simplify withDebug logic

Co-authored-by: Thavarshan <10804999+Thavarshan@users.noreply.github.com>

Author: Copilot

composer.json

@@ -38,6 +38,7 @@
         "friendsofphp/php-cs-fixer": "^3.64",
         "laravel/pint": "^1.21",
         "mockery/mockery": "^1.6",
+        "phpstan/phpstan": "^1.11.5",
         "phpunit/phpunit": "^11.5",
         "squizlabs/php_codesniffer": "^3.7",
         "symfony/var-dumper": "^6.0|^7.2",

src/Fetch/Concerns/ManagesDebugAndProfiling.php

@@ -45,12 +45,7 @@ trait ManagesDebugAndProfiling
     public function withDebug(array|bool $options = true): static
     {
         $this->debugEnabled = $options !== false;
-
-        if (is_array($options)) {
-            $this->debugOptions = array_merge(DebugInfo::getDefaultOptions(), $options);
-        } else {
-            $this->debugOptions = DebugInfo::getDefaultOptions();
-        }
+        $this->debugOptions = array_merge(DebugInfo::getDefaultOptions(), is_array($options) ? $options : []);
 
         return $this;
     }

src/Fetch/Support/FetchProfiler.php

@@ -266,7 +266,7 @@ protected function calculateMetrics(string $requestId): array
         }
 
         if (isset($events['request_sent'])) {
-            $metrics['time_to_first_byte'] = round(($events['response_start'] ?? $endTime - $events['request_sent']) * 1000, 3);
+            $metrics['time_to_first_byte'] = round((($events['response_start'] ?? $endTime) - $events['request_sent']) * 1000, 3);
         }
 
         // Include raw events for detailed analysis