Me too had this issue in the past. You can take the file from any source and copy it to the same folder as popper.min.js (src/assets/plugins/bootstrap/js).
I cannot attach the file here but I found a copy at the following link (v. 3): https://www.tobaccofreekids.org/assets/js/popper.js/dist/umd/
I tried to run the "npm build"-command […]
Cannot find SourceMap 'popper.min.js.map': Error: Can't resolve './popper.min.js.map' in '~/IdeaProjects/angular2demo/src/assets/plugins/bootstrap/js'
@ ./~/script-loader!./src/assets/plugins/bootstrap/js/popper.min.js 1:95-352
@ multi script-loader!./src/assets/plugins/jquery/jquery.min.js script-loader!./src/assets/plugins/bootstrap/js/popper.min.js script-loader!./src/assets/plugins/bootstrap/js/bootstrap.min.js script-loader!./src/assets/js/jquery.slimscroll.js script-loader!./src/assets/js/sidebarmenu.js script-loader!./src/assets/js/custom.js script-loader!./src/assets/plugins/styleswitcher/jQuery.style.switcher.js
You can take the file from any source and copy it to the same folder as popper.min.js (src/assets/plugins/bootstrap/js).
I cannot attach the file here but I found a copy at the following link (v. 3):
https://www.tobaccofreekids.org/assets/js/popper.js/dist/umd/
Regards.
-m