As I wrote on the page about the File Editor add-on, this Visual Studio Code is a nice alternative. WARNING: You need the 64bit version of HA for this. If this add-on is greyed out it means you are running the 32bit version.
So follow the same procedure;
- click Supervisor
- Click Add-on store
- look for this add-on
- click on it and click install
- toggle show in sidebar and start it.
You are now ready to use it