emqx/kuiper: xstream/operators/join_operator.go; 30 LoC

Found a possible issue in [emqx/kuiper](https://www.github.com/emqx/kuiper) at [xstream/operators/join_operator.go](https://github.com/emqx/kuiper/blob/91eacc9baea40bd1dedf0267c18ef39a3296c829/xstream/operators/join_operator.go#L276-L305)

Below is the message reported by the analyzer for this snippet of code. Beware that the analyzer only reports the first issue it finds, so please do not limit your consideration to the contents of the below message.

> reference to right was used in a composite literal at line 281

[Click here to see the code in its original context.](https://github.com/emqx/kuiper/blob/91eacc9baea40bd1dedf0267c18ef39a3296c829/xstream/operators/join_operator.go#L276-L305)

Click here to show the 30 line(s) of Go which triggered the analyzer.

```go
for _, right := range rights {
merged := &xsql.JoinTuple{}
merged.AddTuple(right)
isJoint := false
for _, left := range *set {
ve := &xsql.ValuerEval{Valuer: xsql.MultiValuer(&right, &left, fv)}
result := ve.Eval(join.Expr)
switch val := result.(type) {
case error:
return nil, val
case bool:
if val {
isJoint = true
merged.AddTuples(left.Tuples)
}
default:
return nil, fmt.Errorf("invalid join condition that returns non-bool value %[1]T(%[1]v)", val)
}
}

if excludeJoint {
if len(merged.Tuples) > 0 && (!isJoint) {
newSets = append(newSets, *merged)
}
} else {
if len(merged.Tuples) > 0 {
newSets = append(newSets, *merged)
}
}
}

```

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See the descriptions of the classifications [here](https://github.com/github-vet/rangeclosure-findings#how-can-i-help) for more information.

commit ID: 91eacc9baea40bd1dedf0267c18ef39a3296c829