Complete PHPStan Level 6 (#5305)

* Complete PHPStan Level 6
Fix https://github.com/FreshRSS/FreshRSS/issues/4112
And initiate PHPStan Level 7

* PHPStan Level 6 for tests
* Use phpstan/phpstan-phpunit
* Update to PHPStan version 1.10

* Fix mixed bug

* Fix mixed return bug

* Fix paginator bug

* Fix FreshRSS_UserConfiguration

* A couple more Minz_Configuration bug fixes

* A few trivial PHPStan Level 7 fixes

* A few more simple PHPStan Level 7

* More files passing PHPStan Level 7
Add interface to replace removed class from https://github.com/FreshRSS/FreshRSS/pull/5251

* A few more PHPStan Level 7 preparations

* A few last details

6 files changed, 10 insertions, 8 deletions

diff --git a/app/views/helpers/export/articles.phtml b/app/views/helpers/export/articles.phtml
index cc6a62377..60041339b 100644
--- a/app/views/helpers/export/articles.phtml
+++ b/app/views/helpers/export/articles.phtml
@@ -11,7 +11,7 @@ $articles = array(
 	'items' => array(),
 );
 
-echo rtrim(json_encode($articles, $options), " ]}\n\r\t"), "\n";
+echo rtrim(json_encode($articles, $options) ?: '', " ]}\n\r\t"), "\n";
 $first = true;
 
 if (empty($this->entryIdsTagNames)) {
diff --git a/app/views/helpers/export/opml.phtml b/app/views/helpers/export/opml.phtml
index 4df36b122..5acdff374 100644
--- a/app/views/helpers/export/opml.phtml
+++ b/app/views/helpers/export/opml.phtml
@@ -4,7 +4,7 @@
  * @param array<FreshRSS_Feed> $feeds
  * @return array<array<string,string|null>>
  */
-function feedsToOutlines($feeds, bool $excludeMutedFeeds = false): array {
+function feedsToOutlines(array $feeds, bool $excludeMutedFeeds = false): array {
 	$outlines = [];
 	foreach ($feeds as $feed) {
 		if ($feed->mute() && $excludeMutedFeeds) {
@@ -98,4 +98,6 @@ if (!empty($this->feeds)) {
 }
 
 $libopml = new \marienfressinaud\LibOpml\LibOpml(true);
-echo $libopml->render($opml_array);
+$opml = $libopml->render($opml_array);
+/** @var string $opml */
+echo $opml;
diff --git a/app/views/helpers/javascript_vars.phtml b/app/views/helpers/javascript_vars.phtml
index e108f5a34..03ed96a9e 100644
--- a/app/views/helpers/javascript_vars.phtml
+++ b/app/views/helpers/javascript_vars.phtml
@@ -72,4 +72,4 @@ echo htmlspecialchars(json_encode(array(
 		'unread' => rawurlencode(_i('unread')),
 	),
 	'extensions' => $extData,
-), JSON_UNESCAPED_UNICODE), ENT_NOQUOTES, 'UTF-8');
+), JSON_UNESCAPED_UNICODE) ?: '', ENT_NOQUOTES, 'UTF-8');
diff --git a/app/views/index/logs.phtml b/app/views/index/logs.phtml
index 54b7e1c6b..42be022d6 100644
--- a/app/views/index/logs.phtml
+++ b/app/views/index/logs.phtml
@@ -14,7 +14,7 @@
 	?>
 
 	<?php if (!empty($items)) { ?>
-	<?php $this->logsPaginator->render('logs_pagination.phtml', 0); ?>
+	<?php $this->logsPaginator->render('logs_pagination.phtml'); ?>
 	<div id="loglist-wrapper" class="table-wrapper">
 		<table id="loglist">
 			<thead>
@@ -41,7 +41,7 @@
 		</tbody>
 		</table>
 	</div>
-	<?php $this->logsPaginator->render('logs_pagination.phtml', 0); ?>
+	<?php $this->logsPaginator->render('logs_pagination.phtml'); ?>
 
 
 
diff --git a/app/views/index/normal.phtml b/app/views/index/normal.phtml
index 02b336bf7..ede772a78 100644
--- a/app/views/index/normal.phtml
+++ b/app/views/index/normal.phtml
@@ -40,7 +40,7 @@ $today = @strtotime('today');
 		// We most likely already have the feed object in cache
 		$this->feed = FreshRSS_CategoryDAO::findFeed($this->categories, $this->entry->feedId());
 		if ($this->feed == null) {
-			$this->feed = $this->entry->feed();
+			$this->feed = $this->entry->feed() ?: null;
 			if ($this->feed == null) {
 				$this->feed = FreshRSS_Feed::example();
 			}
diff --git a/app/views/stats/idle.phtml b/app/views/stats/idle.phtml
index fcab1e8e3..d94256860 100644
--- a/app/views/stats/idle.phtml
+++ b/app/views/stats/idle.phtml
@@ -45,7 +45,7 @@
 					<li class="item feed<?= $error_class, $empty_class, $mute_class ?>" title="<?= $error_title, $empty_title ?>">
 						<a class="configure open-slider" href="<?= _url('stats', 'feed', 'id', $feedInPeriod['id'], 'sub', 'idle') ?>" title="<?= _t('gen.action.manage') ?>"><?= _i('configure') ?></a>
 						<?php if (FreshRSS_Context::$user_conf->show_favicons): ?><img class="favicon" src="<?= $feedInPeriod['favicon'] ?>" alt="✇" loading="lazy" /><?php endif; ?>
-						<span title="<?= timestamptodate($feedInPeriod['last_date'], false) ?>"><?= $feedInPeriod['name'] ?>
+						<span title="<?= timestamptodate((int)($feedInPeriod['last_date']), false) ?>"><?= $feedInPeriod['name'] ?>
 							(<?= _t('admin.stats.number_entries', $feedInPeriod['nb_articles']) ?>)</span>
 					</li>
 				<?php } ?>