Add Condition if ParagraphNumb more than Paragraph Content

Add below code inside insertAdAfterParagraph and after $paragraphs = explode( $closing_p, $content );

$count = count($paragraphs);
if ($paragraph_id > $count) {
	$paragraph_id = $count/2;
}

Above code add condition if paragraph set by ads is more than paragraph content set the paragraph ads by paragraph content divide by 2;

ex:
P. Ads = 999
P. Content = 60
P. Ads > P. Content
P. Ads = 60/2
P. Ads = 30.

Ofc, you can change other condition if you like.