renproject/mpc: open/open.go; 5 LoC

Found a possible issue in [renproject/mpc](https://www.github.com/renproject/mpc) at [open/open.go](https://github.com/renproject/mpc/blob/71f4e68af86fbd95962cbe3424e49127a0a9ee22/open/open.go#L157-L161)

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.

>

[Click here to see the code in its original context.](https://github.com/renproject/mpc/blob/71f4e68af86fbd95962cbe3424e49127a0a9ee22/open/open.go#L157-L161)

Click here to show the 5 line(s) of Go which triggered the analyzer.

```go
for i, share := range shareBatch {
if !shamir.IsValid(opener.h, &opener.commitmentBatch[i], &share) {
return nil, nil, ErrInvalidShares
}
}

```

Click here to show extra information the analyzer produced.

```
No path was found through the callgraph that could lead to a function which writes a pointer argument.

No path was found through the callgraph that could lead to a function which passes a pointer to third-party code.

root signature {IsValid 3} was not found in the callgraph; reference was passed directly to third-party code
```

Leave a reaction on this issue to contribute to the project by classifying this instance as a **Bug** :-1:, **Mitigated** :+1:, or **Desirable Behavior** :rocket:
See the descriptions of the classifications [here](https://github.com/github-vet/rangeclosure-findings#how-can-i-help) for more information.

commit ID: 71f4e68af86fbd95962cbe3424e49127a0a9ee22

Start with open/open.go lines 157-161 and inspect the call to shamir.IsValid alongside the analyzer's callgraph notes. Determine whether the reported range-loop pointer finding is a Bug, Mitigated, or Desirable Behavior, then leave the corresponding reaction on the issue.

Written by the indexing model from the issue text.