bootstrap/scss/bootstrap-flex.scss not available at project initialization

[whiletrace]

// error occuring

[21:28:14] gulp-notify: [CSS Error - Line 7] scss/dashing.scss Error: File to import not found or unreadable: bootstrap/scss/bootstrap-flex.scss Parent style sheet: /Users/traceharris/Documents/drupal-lab/web/themes/dashing/scss/dashing.scss on line 7 of scss/dashing.scss

@import "bootstrap/scss/bootstrap-flex.scss";

// reason for the error

https://github.com/twbs/bootstrap/pull/21389

as of Pull request #21389 submitted and merged Dec 21, 2016, bootstrap-flex.scss variant is now obsolete for the release "twbs/bootstrap#v4-dev" as it is now default.

// two possible fixes for this issue

// fix 1

replace the bootstrap @import script at /themes/dashing/scss/dashing.scss

// script is

@import "bootstrap/scss/bootstrap-flex.scss";

// script should be

@import "bootstrap/scss/bootstrap.scss"

// or fix 2

Anchoring an earlier release of bootstrap to the project.