Errro running ng serve - module has no exported member

Question

Something has gotten misconfigured in my app. I've returned to a commit which I know was working before the "incident", but I get errors when running ng serve (listed below) and the app fails to load. The errors refer to files in node_modules which I do not edit. I have tried npm uninstall followed by npm install for the modules @angular/common and @angular/forms but this has no effect. At this point I don't know what to do.

[default] Checking started in a separate process...

[default] /Users/carlson/dev/a2/manuscripta2b/node_modules/@angular/common/src/common.d.ts:19:10 
    Module '"/Users/carlson/dev/a2/manuscripta2b/node_modules/@angular/core/index"' has no exported member 'Version'.

[default] /Users/carlson/dev/a2/manuscripta2b/node_modules/@angular/common/src/version.d.ts:13:10 
    Module '"/Users/carlson/dev/a2/manuscripta2b/node_modules/@angular/core/index"' has no exported member 'Version'.

[default] /Users/carlson/dev/a2/manuscripta2b/node_modules/@angular/forms/src/version.d.ts:13:10 
    Module '"/Users/carlson/dev/a2/manuscripta2b/node_modules/@angular/core/index"' has no exported member 'Version'.
[default] /Users/carlson/dev/a2/manuscripta2b/src/app/editor/editor/editor/editor.component.ts:23:14 

Answer 1

I set up new product with ng new foo, then copied the src directory from the damaged app, then slowly rebuilt the dependencies in package.json.