Create a non uniform table in Google Docs Apss Script

Question

I am looking at two methods to achieve what I want. Neither have been successful.

What I want: By clicking a menu button I want a table inserted in to the Google Doc I am editing (In MS Word I would just have used a macro). The table is Non uniform but all rows should fill the width of the document.

Method 1: I made the table in another Google Doc and tried to "copy/paste" the content, but I constant end up with an error:

var docToCopyID = '---The Id of the Google Doc with only a table in it---';
var bodyToCopy = DocumentApp.openById(docToCopyID).getBody();
var tableToCopy = bodyToCopy.getTables[0];

var docBody = DocumentApp.getActiveDocument().getBody();

docBody.appendTable(tableToCopy);

The Error I get is (translated from Danish): Exception: Unexpected error, method or propperty appendTable when object DocumentApp.Body should be read.

Method 2: I tried to build the table by code, but the result is that there is a blank line between the cells:

  var docBody = DocumentApp.getActiveDocument().getBody();
  
  var cells1 = [
  ['Beslutning'],
  ['']
  ];
  var cells2 = [
  ['Ansvarlig','','Dato','dd.mm.yyyy']
  ];
  
  docBody.appendTable(cells1);
  docBody.appendTable(cells2);

Whether I end up with clean code or using the copy/paste method is indifferent for me. Thanks in advance!