Here is the best way, for me, to add code inside word:

1. Go to Insert tab, Text section, click Object button (it's on the right)
2. Choose OpenDocument Text which will open a new embedded word document
3. Copy and paste your code from Visual Studio / Eclipse inside this embedded word page
4. Save and close

Advantages

The result looks very nice. Here are the advantages of this method:

• The code keeps its original layout and colors
• The code is separated from the rest of the document, as if it was a picture or a chart
• Spelling errors won't be highlighted in the code (this is cool !)

And it takes only few seconds.

The JavaScript console was removed from Visual Studio 2019. You have basically 2 options:

1. Install Visual Studio 2017 side-by-side Visual 2019 (or install Visual 2017 on another computer) and use VS 2017 to develop Office Add-ins.
2. Use the Dev Tools of the browser that the add-in is using to run. For which browser your add-in is using, see Browsers used by Office Web Add-ins.