WebSocket Connection Memory Leak in RealtimeClient

[tanmaysharma2001]

Description

There is a memory leak in RealtimeClient._teardownConnection() where WebSocket connections were not properly closed before being nullified, causing connections to remain open in memory indefinitely. I have fixed that.

The original implementation in packages/core/realtime-js/src/RealtimeClient.ts:596-606 would set WebSocket event handlers to null and nullify the connection reference without first ensuring the WebSocket was properly closed:

private _teardownConnection(): void {
  if (this.conn) {
    this.conn.onopen = null
    this.conn.onerror = null
    this.conn.onmessage = null
    this.conn.onclose = null
    this.conn = null  // reference nullified without ensuring closure
  }
}

I intend to submit a PR for this issue.

Suggested solution

Enhanced _teardownConnection() to explicitly close WebSocket connections before cleanup:

private _teardownConnection(): void {
  if (this.conn) {
    // Ensure connection is properly closed first
    if (
      this.conn.readyState === SOCKET_STATES.open ||
      this.conn.readyState === SOCKET_STATES.connecting
    ) {
      try {
        this.conn.close()
      } catch (e) {
        this.log('error', 'Error closing connection', e)
      }
    }

    this.conn.onopen = null
    this.conn.onerror = null
    this.conn.onmessage = null
    this.conn.onclose = null
    this.conn = null
  }
  this._clearAllTimers()
  this.channels.forEach((channel) => channel.teardown())
}

Alternative

No response

Additional context

No response

Validations

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