Change nukeSet() from public to internal

I'm using Truffle `V5.1.13` and in my contracts `pragma solidity ^0.5.1;`
Having nukeSet be public causes truffle tests to fail with the following error message

```
    "before all" hook: prepare suite: TypeError: Cannot read property 'typeClass' of undefined
```
Changing nukeSet() to be internal allows tests to go through

