WritePoint function: panic send on Closed channel

[XianwuLin]

Specifications

• Client Version: v2.13.0
• InfluxDB Version: v2.7.1
• Platform: x86

Steps to reproduce

1. Use this library to continuously write data to influxdb
2. kill influxdb
3. sometimes program error: send on closed channel
   

Expected behavior

Plugin should be able to correctly handle the situation where influxdb is closed and give an error instead of panic directly.

Actual behavior

panic

Additional info

No response