Added guard to handle missing content-type

Author: lachiebol

Annotations/AnnotationGenerator.php

@@ -890,7 +890,7 @@ protected function getExampleIfAvailable(string $url, bool $useLocalToken = fals
             || stripos($response['data'], '<result />') !== false
             || trim($response['data']) === '[]'
             || (stripos($url, 'format=tsv') !== false && trim($response['data']) === 'No data available')
-            || !preg_match("/(json|xml|tsv)/", $response['headers']['content-type']) // Some ask for xml/json/tsv but return image/png, shouldn't be treated as xml
+            || !preg_match("/(json|xml|tsv)/", $response['headers']['content-type'] ?? '') // Some ask for xml/json/tsv but return image/png, shouldn't be treated as xml
         ) {
             return '';
         }