When change registerGauge 3rd parameter array size, it breaks

**Error: array_combine(): Both parameters should have an equal number of elements**
```
PROMETHEUS_NAMESPACE=namespace
PROMETHEUS_METRICS_ROUTE_ENABLED=true
PROMETHEUS_METRICS_ROUTE_PATH=metrics
PROMETHEUS_METRICS_ROUTE_MIDDLEWARE=null
PROMETHEUS_STORAGE_ADAPTER=redis
PROMETHEUS_REDIS_PREFIX=PROMETHEUS_
```