* refactor: Replace ctx.Done() with ctx.Err()
Prior to this commit we checked for context cancellation with a select
block and context.Context.Done() without multiplexing over any other
channel like:
select {
case <-ctx.Done():
// handle cancellation
default:
// fallthrough
}
This commit replaces those type of blocks with a simple check of
ctx.Err(). This has the following benefits:
* Calling ctx.Err() is much faster than entering a select block.
* ctx.Done() allocates a channel when called for the first time.
* Testing the result of ctx.Err() is a reliable way of determininging if
a context.Context value has been canceled.
* fix: Fix data race in execDeleteTagValueEntry()