ehtherpad 2.5.1 /stats/prometheus

[Loki-Afro]

Describe the bug
/stats/prometheus returns 500 after the first call

To Reproduce
Steps to reproduce the behavior:

1. run etherpad
2. access /stats/prometheus
3. see metrics
4. access /stats/prometheus
5. receive http status code 500 ;)

Expected behavior
no 500

Screenshots
If applicable, add screenshots to help explain your problem.

Server (please complete the following information):

• Etherpad version: 2.5.1
• OS: container image

Additional context

i also noted that /stats and /stats/prometheus do not contain the same metrics, the prometheus one is missing the most important ones to me
totalUsers and activePads
also the http related ones appear to be absent

[Loki-Afro]

error from log

[2025-10-16T10:08:44.089] [ERROR] settings - Error: A metric with the name ueberdb_stats has already been registered.
    at Registry.registerMetric (/home/zarathustra/code/etherpad-lite/node_modules/.pnpm/prom-client@15.1.3/node_modules/prom-client/lib/registry.js:103:10)
    at new Metric (/home/zarathustra/code/etherpad-lite/node_modules/.pnpm/prom-client@15.1.3/node_modules/prom-client/lib/metric.js:64:13)
    at new Gauge (/home/zarathustra/code/etherpad-lite/node_modules/.pnpm/prom-client@15.1.3/node_modules/prom-client/lib/gauge.js:21:3)
    at monitor (/home/zarathustra/code/etherpad-lite/src/node/prometheus.ts:9:19)
    at <anonymous> (/home/zarathustra/code/etherpad-lite/src/node/hooks/express/specialpages.ts:43:29)
    at Layer.handleRequest (/home/zarathustra/code/etherpad-lite/node_modules/.pnpm/router@2.2.0/node_modules/router/lib/layer.js:152:17)
    at next (/home/zarathustra/code/etherpad-lite/node_modules/.pnpm/router@2.2.0/node_modules/router/lib/route.js:157:13)
    at Route.dispatch (/home/zarathustra/code/etherpad-lite/node_modules/.pnpm/router@2.2.0/node_modules/router/lib/route.js:117:3)
    at handle (/home/zarathustra/code/etherpad-lite/node_modules/.pnpm/router@2.2.0/node_modules/router/index.js:435:11)
    at Layer.handleRequest (/home/zarathustra/code/etherpad-lite/node_modules/.pnpm/router@2.2.0/node_modules/router/lib/layer.js:152:17)
    at /home/zarathustra/code/etherpad-lite/node_modules/.pnpm/router@2.2.0/node_modules/router/index.js:295:15
    at processParams (/home/zarathustra/code/etherpad-lite/node_modules/.pnpm/router@2.2.0/node_modules/router/index.js:582:12)
    at next (/home/zarathustra/code/etherpad-lite/node_modules/.pnpm/router@2.2.0/node_modules/router/index.js:291:5)
    at jsonParser (/home/zarathustra/code/etherpad-lite/node_modules/.pnpm/body-parser@2.2.0/node_modules/body-parser/lib/types/json.js:100:7)
    at Layer.handleRequest (/home/zarathustra/code/etherpad-lite/node_modules/.pnpm/router@2.2.0/node_modules/router/lib/layer.js:152:17)
    at trimPrefix (/home/zarathustra/code/etherpad-lite/node_modules/.pnpm/router@2.2.0/node_modules/router/index.js:342:13)
[2025-10-16T10:08:44.138] [ERROR] settings - Error: Request aborted
    at onaborted (/home/zarathustra/code/etherpad-lite/node_modules/.pnpm/express@5.1.0/node_modules/express/lib/response.js:922:15)
    at Immediate.<anonymous> (/home/zarathustra/code/etherpad-lite/node_modules/.pnpm/express@5.1.0/node_modules/express/lib/response.js:964:9)
    at process.processImmediate (node:internal/timers:491:21)