Cannot run reslate as a dependency.

[tarrnobi]

Bug Description
Following the instructions at https://github.com/Mermade/reslate to set it up I:

1. Created my node project using npm init
2. Run npm i --save-dev reslate
3. Run npx reslate init
4. Run npx reslate serve

The serve fails with the following message "no such file or directory, stat ...$SLATEDIR` (clearer in the image).

I'm not sure if this helps, but If I navigate to node_modules\reslate\package.json and replace all of the $SLATEDIR variables with ../.., it successfully serves. It seems like it's passing the slatedir variable through for the first part of the call (build), but not for the serve itself.

Screenshots
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Browser (please complete the following information):

• OS: Windows 10
• Node: v14.15.1

Last upstream Slate commit (run git log --author="Robert Lord" | head -n 1):
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