Exception thrown from WebPack

Environment: MacOS 10.11.6

Installed yo and generator-aspnetcore and then created a new project. Ran "npm install".

Opened the project in Visual Code and entered "npm run"in the terminal, and the following was displayed:

bash-3.2$ npm start

> app@0.0.0 start /Users/krallen/Projects/DotNetCore/d2llontario
> node run

Starting 'start'...
Starting 'clean'...
Finished 'clean' after 36ms
Starting 'appsettings'...
Finished 'appsettings' after 4ms
Error
at webpack (/Users/krallen/Projects/DotNetCore/d2llontario/node_modules/webpack/lib/webpack.js:19:9)
at resolve (/Users/krallen/Projects/DotNetCore/d2llontario/run.js:159:24)
at Promise.resolve.then.then.then (/Users/krallen/Projects/DotNetCore/d2llontario/run.js:156:17)
bash-3.2$

Line 19 of the Webpack.js file contains the line:

throw new WebpackOptionsValidationError(webpackOptionsValidationErrors);

This seems to come from the loading of a 'schema' file:

const webpackOptionsSchema = require("../schemas/webpackOptionsSchema.json");

I have not modified anything, so why should this be occurring?

Reproduce the failure with npm start, then inspect run.js around lines 156-159 and the webpack call at node_modules/webpack/lib/webpack.js:19. Compare the generated webpack options with schemas/webpackOptionsSchema.json and use the reported validation errors to identify the mismatch; done means npm start completes without this exception.

Written by the indexing model from the issue text.