Extend PHPStan ignore config to support multiple PHP versions

phpstan.neon

@@ -2,6 +2,15 @@ parameters:
     level: max
     paths:
     - src
+
+    # Legacy stuff to be periodically reviewed
+    ignoreErrors:
+    -   # This error only occurs on PHP 8.1 and can be removed after it's dropped
+        identifier: offsetAccess.nonOffsetAccessible
+        path: src/Form/Type/SubmitTimerType.php
+        count: 1
+        reportUnmatched: false
+
     excludePaths:
     # Obsolete code
     - src/Command/StatisticsCommand.php

src/Form/Type/SubmitTimerType.php

@@ -98,8 +98,6 @@ public function buildView(FormView $view, FormInterface $form, array $options):
         $ip = $this->requestStack->getMainRequest()?->getClientIp() ?? self::NO_IP;
         $ts = $this->getTimestampMilliseconds();
         $secret = $options['secret'];
-
-        assert(is_array($view->vars));
         $view->vars['value'] = \base64_encode(implode('|', [$ip, $ts, hash('sha256', "$ts|$ip|$secret")]));
     }