"syntax error, unexpected '' (T_ENCAPSED_AND_WHITESPACE)" while using HEREDOC syntax in PHP7.2, but PHP7.4 is fine

if (array_key_exists('icon_path', $changedAttributes)) {
    $iconFile = $changedAttributes["icon_path"];
}

Why does $iconFile = $changedAttributes["icon_path"]; line gives me below error in php 7.2? Even though I change it to single quotations ['icon_path'] doesn't solve the problem.

syntax error, unexpected '' (T_ENCAPSED_AND_WHITESPACE), expecting '-' or identifier (T_STRING) or variable (T_VARIABLE) or number (T_NUM_STRING)

But in php 7.4 there's no problem at all.

I checked my code with this version checker https://www.piliapp.com/php-syntax-check/ 7.2 gives me this error but 7.4 works fine.

It was an indent issue. My code has below JavaScript code.

public function reloadPageOnEdit()
{
    return <<<JSCRIPT
        <script>
            function openWindowReload(link) {
                var href = link.href;
                
                document.location.reload(true);
                window.open(href,'_self');
            }
        </script>
        JSCRIPT;
}

and I indented it fully left. It solved the problem. Even there's no issue in 7.4 but 7.2. I got confused because the code failed on somewhere else.

    public function reloadPageOnEdit()
    {
        return <<<JSCRIPT
<script>
    function openWindowReload(link) {
        var href = link.href;
        
        document.location.reload(true);
        window.open(href,'_self');
    }
</script>
JSCRIPT;
    }