When carrying out the following steps make backups of the original files before overwriting (e.g. rename the original file to extension.js.backup before pasting in the new file)

1. Rename extension.txt to extension.js and place in the folder:
C:\Users\"your windows login"\.vscode\extensions\johnsoevans.topas-editor-1.1.6\dist\

2. Rename package.txt to package.json and place in:
C:\Users\"your windows login"\.vscode\extensions\johnsoevans.topas-editor-1.1.6\

3. Rename settings.txt to settings.json and place in:
C:\Users\"your windows login"\AppData\Roaming\Code\User\

reload VScode 
Ctrl + Shift + P => type Developer: Reload Window