Fix #882 - Error thrown on PHP 8 when attempting to count() null values

qa-include/pages/hot.php

@@ -31,7 +31,7 @@ require_once QA_INCLUDE_DIR . 'app/q-list.php';
 // Get list of hottest questions, allow per-category if QA_ALLOW_UNINDEXED_QUERIES set in qa-config.php
 
 $categoryslugs = QA_ALLOW_UNINDEXED_QUERIES ? qa_request_parts(1) : null;
-$countslugs = @count($categoryslugs);
+$countslugs = $categoryslugs === null ? null : count($categoryslugs);
 
 $start = qa_get_start();
 $userid = qa_get_logged_in_userid();

qa-include/pages/unanswered.php

@@ -36,7 +36,7 @@ if (QA_ALLOW_UNINDEXED_QUERIES)
 else
 	$categoryslugs = null;
 
-$countslugs = @count($categoryslugs);
+$countslugs = $categoryslugs === null ? null : count($categoryslugs);
 $by = qa_get('by');
 $start = qa_get_start();
 $userid = qa_get_logged_in_userid();

qa-include/qa-feed.php

@@ -74,7 +74,7 @@ function qa_feed_not_found()
 function qa_feed_load_ifcategory($categoryslugs, $allkey, $catkey, &$title,
 	$questionselectspec1 = null, $questionselectspec2 = null, $questionselectspec3 = null, $questionselectspec4 = null)
 {
-	$countslugs = @count($categoryslugs);
+	$countslugs = $categoryslugs === null ? null : count($categoryslugs);
 
 	list($questions1, $questions2, $questions3, $questions4, $categories, $categoryid) = qa_db_select_with_pending(
 		$questionselectspec1,
@@ -165,7 +165,7 @@ switch ($feedtype) {
 		break;
 }
 
-$countslugs = @count($categoryslugs);
+$countslugs = $categoryslugs === null ? null : count($categoryslugs);
 
 if (!isset($feedoption))
 	qa_feed_not_found();