[BUGFIX] Fix missing array key failure

Classes/Service/SpanParserService.php

@@ -142,7 +142,7 @@ class SpanParserService extends AbstractParserService {
 			if (ExtensionManagementUtility::isLoaded('headless')) {
 				// when EXT:headless is present, content will be escaped (JSON output), so we got to add some small details:
 				$search[$termName] = '/' .
-					'<span ' . preg_quote($term['pre'], '/') .
+					'<span ' . preg_quote($term['pre'] ?? '', '/') .
 					'class=\\\\"([^"]*?)' . $searchClass . '([^"]*?)\\\\"' .
 					preg_quote($term['post'], '/') . '>' .
 					'\s*?' . preg_quote($term['term'], '/') . '\s*?' .
@@ -150,7 +150,7 @@ class SpanParserService extends AbstractParserService {
 					'/i';
 			} else {
 				$search[$termName] = '/' .
-					'<span ' . preg_quote($term['pre'], '/') .
+					'<span ' . preg_quote($term['pre'] ?? '', '/') .
 					'class="([^"]*?)' . $searchClass . '([^"]*?)"' .
 					preg_quote($term['post'], '/') . '>' .
 					'\s*?' . preg_quote($term['term'], '/') . '\s*?' .
@@ -164,7 +164,7 @@ class SpanParserService extends AbstractParserService {
 				$termName
 			);
 
-			if (trim($term['pre']) !== '' || trim($term['post']) !== '' || trim($term['classAttribute']) !== '') {
+			if (trim($term['pre'] ?? '') !== '' || trim($term['post']) !== '' || trim($term['classAttribute']) !== '') {
 				$attributes = trim($term['pre'] . ' ' . $term['post'] . ' ' . $term['classAttribute']);
 				$replace[$termName] = '<span ' . $attributes . '>' . $replace[$termName] . '</span>';
 			}