When reloading HLS, it directly operates unpublish and publish. At this
time, if HLS is pushed, an exception may occur.
The reason is that these two coroutines operated on the HLS object at
the same time, causing a null pointer.
Solution: Use asynchronous reload. During reload, only set variables and
let the message processing coroutine implement the reload.
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Co-authored-by: Haibo Chen <495810242@qq.com>
Co-authored-by: chundonglinlin <chundonglinlin@163.com>
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