HAS_NXSDK can be false even when nxsdk is installed

[hunse]

I think the main way for this to happen is if our snip_maker import fails.

We should move the snip_maker import into the if HAS_NXSDK block below where we do other sub-imports within nxsdk. We can wrap it in its own try block there if we want (to just not do the snip_maker monkeypatch if its not there), or just fail completely, but at least then it would be clear why things aren't working.

[hunse]

I think I encountered this when using an inappropriate NxSDK version, which didn't have snip_maker.