[4.9.6] webpack produces a warning -> "export 'createUnarySpacing' was not found in '@material-ui/system'"

[nratter]

• The issue is present in the latest release.
• I have searched the issues of this repository and believe that this is not a duplicate.

Current Behavior 😯

WARNING in ./node_modules/@material-ui/core/esm/styles/createSpacing.js 14:18-36
"export 'createUnarySpacing' was not found in '@material-ui/system'
@ ./node_modules/@material-ui/core/esm/styles/createMuiTheme.js
@ ./node_modules/@material-ui/core/esm/styles/defaultTheme.js
@ ./node_modules/@material-ui/core/esm/styles/useTheme.js
@ ./node_modules/@material-ui/core/esm/LinearProgress/LinearProgress.js
@ ./node_modules/@material-ui/core/esm/LinearProgress/index.js
@ ./app/components/OrganizationSignup2/Loading.jsx

Expected Behavior 🤔

No warning.

Your Environment 🌎

Tech	Version
Material-UI	v4.9.6
React	v16.12.0
TypeScript	v3.8.3

[oliviertassinari]

@eps1lon Oops, it had to happen! 😆

[oliviertassinari]

It should be solved with @material-ui/core@4.9.7.