Fix: PHPStan issues fixes

dashboards.module

...les/dashboards_comments/src/Plugin/Dashboard/Comments.php

...les/dashboards_matomo/src/Plugin/Dashboard/MatomoBase.php

.../dashboards_statistic/src/Plugin/Dashboard/MostReaded.php

...s/dashboards_webform/src/Plugin/Dashboard/Submissions.php

src/DashboardsPermissions.php

src/Entity/DashboardViewBuilder.php

src/Form/DashboardLayoutBuilderForm.php

src/Form/FormAlter.php

src/Plugin/Block/DashboardBlock.php

src/Plugin/Dashboard/Account.php

src/Plugin/Dashboard/AddContentMenu.php

src/Plugin/Dashboard/ErrorReport.php

src/Plugin/Dashboard/NodeStatistics.php

src/Plugin/Dashboard/ReportNotFound.php

src/Plugin/Dashboard/StatusUpdates.php

src/Plugin/Dashboard/SystemInfo.php

src/Plugin/Dashboard/ViewEmbed.php

src/Plugin/DashboardBase.php

src/Plugin/Derivative/DashboardBlock.php