Warning: Incorrect usage of related-filter or function

The related-filter or function can only be applied to a single Record.

• RelatedExtension->checkforContent()
• RelatedExtension->getRelatedContent() - line 101
• __TwigTemplate_8c975bf8…->doDisplay() - line 55
• Template->displayWithErrorHandling() - line 394
• Template->display() - line 367