Throw TypeError if passed an offset not supported on the underlying OS

[a-sully]

Fixes #31

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[a-sully]

Please let me know if you'd prefer this to be non-normative text, or if we should add that in addition to the algorithm changes

[annevk]

I see that we also have "throw an {{InvalidStateError}}" which presumably needs to be:

[=throw=] an "{{InvalidStateError}}" {{DOMException}}

Given that, should this be a JS TypeError or should this be of the DOMException variety as well?

And yeah, normally the non-normative description does call out that the algorithm can throw exceptions and which kinds.

[a-sully]

I see that we also have "throw an {{InvalidStateError}}" which presumably needs to be:

[=throw=] an "{{InvalidStateError}}" {{DOMException}}

Huh, looks like I missed some in #70? Must've been lost while resolving merge conflicts or something...

Given that, should this be a JS TypeError or should this be of the DOMException variety as well?

Prior discussion (#31 (comment)) suggested using TypeError, though I'm happy to make this a DomException if we've changed our mind now that we're seeing this in context with the rest of the algorithm

[annevk]

I don't have a strong opinion on what exception to use so I'll defer to you on that. Looks good modulo the nit.