CompileError: Begins at CSS selector undefined

[blascokoa]

On development it works well, but when I try to make a production build, yarn returns the following error:

yarn run v1.22.19
$ react-scripts build
Creating an optimized production build...
Failed to compile.

Lexical error on line 1: Unrecognized text.
  Erroneous area:
1: $loading-transition-speed / 20
^..^
CompileError: Begins at CSS selector undefined

Solved modifying the line 33 of file:
node_modules/react-awesome-button/src/styles/base/custom-properties.scss

from:
--loading-transition-end-speed: #{calc($loading-transition-speed / 20)} ;
to
--loading-transition-end-speed: calc(#{$loading-transition-speed} / 20);