https://github.com/yang991178/fluent-reader#build-from-source suggests npm run electron, which does not work, so I tried:

electron28 ./dist/electron.js

% pkg iinfo electron
electron28-28.3.3
% npm run electron

> fluent-reader@1.1.4 electron
> electron ./dist/electron.js

/usr/home/grahamperrin/dev/fluent-reader/node_modules/electron/index.js:17
    throw new Error('Electron failed to install correctly, please delete node_modules/electron and try installing again');
    ^

Error: Electron failed to install correctly, please delete node_modules/electron and try installing again
    at getElectronPath (/usr/home/grahamperrin/dev/fluent-reader/node_modules/electron/index.js:17:11)
    at Object.<anonymous> (/usr/home/grahamperrin/dev/fluent-reader/node_modules/electron/index.js:21:18)
    at Module._compile (node:internal/modules/cjs/loader:1358:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1416:10)
    at Module.load (node:internal/modules/cjs/loader:1208:32)
    at Module._load (node:internal/modules/cjs/loader:1024:12)
    at Module.require (node:internal/modules/cjs/loader:1233:19)
    at require (node:internal/modules/helpers:179:18)
    at Object.<anonymous> (/usr/home/grahamperrin/dev/fluent-reader/node_modules/electron/cli.js:3:18)
    at Module._compile (node:internal/modules/cjs/loader:1358:14)

Node.js v20.14.0
% electron28 ./dist/electron.js
[77731:0630/191651.898667:ERROR:nss_util.cc(357)] After loading Root Certs, loaded==false: NSS error code: -8018
App threw an error during load
Error: Error: font-list can not run on freebsd.
    at 4538 (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:129827)
    at t (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:189853)
    at 5807 (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:158974)
    at t (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:189853)
    at 9465 (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:163890)
    at t (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:189853)
    at 3571 (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:153054)
    at t (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:189853)
    at /usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:189963
    at Object.<anonymous> (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:189972)
A JavaScript error occurred in the main process
Uncaught Exception:
Error: Error: font-list can not run on freebsd.
    at 4538 (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:129827)
    at t (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:189853)
    at 5807 (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:158974)
    at t (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:189853)
    at 9465 (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:163890)
    at t (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:189853)
    at 3571 (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:153054)
    at t (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:189853)
    at /usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:189963
    at Object.<anonymous> (/usr/home/grahamperrin/dev/fluent-reader/dist/electron.js:2:189972)
Gtk-Message: 19:16:52.450: Failed to load module "appmenu-gtk-module"
load: 3.01  cmd: electron 77733 [uwait] 144.52r 0.08u 0.02s 0% 122628k

As far I can tell, the Gtk-Message is negligible.

Can anyone tell/guess why a window does not appear?