Is there a C# API to iterate over all the content while ignoring choices?

I have a custom "sub-format" for my content.
```
John: Hello!
```

I'll parse this `John` and check if John is a character in my game, so if I made a typo:

```
Jonh: Hello!
```

I can show an error.

I already know how to do the above, with a caveat: the error only shows up when the player actually runs into `Jonh: Hello!`. If I have an ink script like this:

```
+ [hello]
Jonh: Hello!
+ [good night]
John: Good night.
```

and the player chooses `[good night]`, then it doesn't show errors. I'd like to make an editor button that catches these kinds of errors beforehand, before the player even plays the script.

How could I do this? I think the simplest way is just to iterate over all the content and validate them, but I don't know how to do it with the API.