Function beforeUnregistration

beforeUnregistration(listenerId, fn): void
JMap.Event.Extension.on.beforeUnregistration

This event is triggered just before an extension will be unregistered.
Parameters
- listenerId: string
  Your listener id (must be unique)
- fn: ((params) => void)
  Your listener function
  - - (params): void
    - Parameters
      params: JExtensionEventParams
      Returns void
Returns void
Example
```
// log a message in the console each time an extension will be unregistered
JMap.Event.Extension.on.beforeUnregistration(
  "custom-core-extension-beforeUnregistration",
  params => console.log(`Extension id="${params.extensionId}" will be unregistered`)
)
```