angular-contents error after <<npm i angular-contents>>

[mclr47]

Error: ./node_modules/angular-contents/src/contents-link.directive.ts
Module build failed (from ./node_modules/@ngtools/webpack/src/index.js):
Error: /Users/arc/Documents/web_Dev2/ex/ang-toc-npm/node_modules/angular-contents/src/contents-link.directive.ts is missing from the TypeScript compilation. Please make sure it is in your tsconfig via the 'files' or 'include' property.
The missing file seems to be part of a third party library. TS files in published libraries are often a sign of a badly packaged library. Please open an issue in the library repository to alert its author and ask them to package the library using the Angular Package Format (https://goo.gl/jB3GVv).