[BUGFIX] Properly setup AbstractSitemapGenerator construction

When calling /sitemal.xml on a page, GoogleSitemapController.php did not properly construct any SitemapGenerator, always resulting in an $pageId=0 not Found error.

Classes/Controller/GoogleSitemapController.php

@@ -44,11 +44,31 @@ class GoogleSitemapController extends ActionController {
 		$sitemapType = $this->getSitemapType();
 		if (isset($GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['sg_seo']['sitemap'][$sitemapType])) {
 			$userFuncRef = $GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['sg_seo']['sitemap'][$sitemapType];
-			$params = array();
-			GeneralUtility::callUserFunction($userFuncRef, $params, $this);
-		}
-		else {
-			header('HTTP/1.0 400 Bad request', true, 400);
+
+			$params = [];
+			// since our AbstractSitemapGenerator will need specific details in its __construct,
+			// we need to be in charge of makeInstance.
+			// This code is taken from GeneralUtility::callUserFunction
+			$parts = explode('->', $userFuncRef);
+
+			// Create object
+			// ARGS: int $pageId = 0, SiteLanguage $language = NULL, bool $enableFilter = TRUE
+			$abstractSitemapGeneratorArgs = [
+				$GLOBALS['TSFE']->id,
+				$GLOBALS['TSFE']->language,
+				TRUE
+			];
+			$classObj = GeneralUtility::makeInstance($parts[0], ...$abstractSitemapGeneratorArgs);
+			$callable = [$classObj, (string) $parts[1]];
+			if (is_callable($callable)) {
+				// Call method:
+				call_user_func_array($callable, [&$params, &$ref]);
+			} else {
+				$errorMsg = 'No method name \'' . $parts[1] . '\' in class ' . $parts[0];
+				throw new \InvalidArgumentException($errorMsg, 1294585865);
+			}
+		} else {
+			header('HTTP/1.0 400 Bad request', TRUE, 400);
 			header('Content-type: text/plain');
 			echo 'No generator found for type \'' . $sitemapType . '\'';
 		}
@@ -59,7 +79,7 @@ class GoogleSitemapController extends ActionController {
 	/**
 	 * Determines what sitemap should be send
 	 *
-	 * @return	string
+	 * @return    string
 	 */
 	protected function getSitemapType(): string {
 		$type = GeneralUtility::_GP('sitemap');