Google Analytics / JavaScript: Get Client ID

I'm working in WordPress and I have this block of JS code on my page. I'm trying to write the Google Analytic Client ID in the console, however, I'm getting the following console error:

Uncaught ReferenceError: ga is not defined

<script>

    ga('create', 'UA-123456789-1', 'auto');
    ga('send', 'pageview');
    
    ga(function(tracker) {
      console.log(tracker.get('clientId'));
      /* Your other code here */
    });

</script>

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What am I missing?  Any help would be appreciated.  Thanks!