D:\Dev\webextension-test>npm-run --version
5.0.1

D:\Dev\webextension-test>npm-run web-ext --version
Error: spawn web-ext ENOENT
    at Process.ChildProcess._handle.onexit (internal/child_process.js:201:19)
    at onErrorNT (internal/child_process.js:379:16)
    at process._tickCallback (internal/process/next_tick.js:114:19)
    at Function.Module.runMain (module.js:705:11)
    at startup (bootstrap_node.js:193:16)
    at bootstrap_node.js:660:3

D:\Dev\webextension-test>npm-run where web-ext
D:\Dev\webextension-test\node_modules\.bin\web-ext
D:\Dev\webextension-test\node_modules\.bin\web-ext.cmd
C:\Users\Owner\AppData\Roaming\npm\web-ext
C:\Users\Owner\AppData\Roaming\npm\web-ext.cmd