Parse error: RTF text outside of group

I am getting this error after my rtf document is converted and I'm moving on to a new document to convert

$document = new \RtfHtmlPhp\Document($note_object->rtf);
$formatter = new \RtfHtmlPhp\Html\HtmlFormatter('UTF-8');
$plain_text = (strip_tags($formatter->Format($document)));

after I convert my rtf document to plain text, I'm then sending it through sftp, but when I move on to the next document to convert, it crashes with the message 'Parse error: RTF text outside of group'

I'm not sure what is causing this as I know that the object being send into the formatter is indeed RTF

More debug info:

Trace:
	Array
	(
	    [0] => Array
	        (
	            [args] => Array
	                (
	                    [0] => 1024
	                    [1] => Parse error: RTF text outside of group.
	                    [2] => /var/www/html/mysite/vendor/henck/rtf-to-html/src/Document.php
	                    [3] => 286
	                    [4] => Array
	                        (
	                            [text] => RtfHtmlPhp\Text Object
	                                (
	                                    [text] => This was created by the edito
	                                )

	                            [terminate] =>
	                            [err] => Parse error: RTF text outside of group.
	                        )

	                )

	        )

	    [1] => Array
	        (
	            [file] => /var/www/html/mysite/vendor/henck/rtf-to-html/src/Document.php
	            [line] => 286
	            [function] => trigger_error
	            [args] => Array
	                (
	                    [0] => Parse error: RTF text outside of group.
	                )

	        )

	    [2] => Array
	        (
	            [file] => /var/www/html/mysite/vendor/henck/rtf-to-html/src/Document.php
	            [line] => 326
	            [function] => ParseText
	            [class] => RtfHtmlPhp\Document
	            [type] => ->
	            [args] => Array
	                (
	                )

	        )

	    [3] => Array
	        (
	            [file] => /var/www/html/mysite/vendor/henck/rtf-to-html/src/Document.php
	            [line] => 17
	            [function] => Parse
	            [class] => RtfHtmlPhp\Document
	            [type] => ->
	            [args] => Array
	                (
	                    [0] => This was created by the editor
	                )

	        )

	    [4] => Array
	        (
	            [file] => /var/www/html/mysite/private/Controllers/Jobs/Healthelink/Dischargesummary.php
	            [line] => 105
	            [function] => __construct
	            [class] => RtfHtmlPhp\Document
	            [type] => ->
	            [args] => Array
	                (
	                    [0] => This was created by the editor
	                )

	        )

Reproduce the failure while converting successive documents, then inspect src/Document.php around lines 286, 326, and 17, where ParseText and Parse process the reported text. Compare the input passed from the caller at Dischargesummary.php line 105 with the parser's group handling; done means the sequence converts without the reported parse error.