TypeError: Cannot read properties of undefined (reading 'assets')

[Tom-H2oThermo]

I have created an Excel add-in which I will be selling on the Azure Marketplace. I was working on getting SSO working using the OfficeAddinDevKit and at one point ran npm build to recreate all my node modules. Apparently this upgraded my webpack module from V4 to V5 and then when I ran "npm start" I was getting 89 errors with long and cryptic error messages. I saw on this page that a solution is to install the node-polyfill-webpack-plugin, which I did. Now when I run "npm start" I get only 10 errors with readable messages, but I don't know how to solve these errors (see output below). Could you possibly point me in the right direction as to how to solve these problems? Thank you.

PS C:\Users\tomte\OneDrive\Documents\GitHub\H2oThermo_App-Development1> npm start

excel-custom-functions@0.0.1 prestart
npm run build
excel-custom-functions@0.0.1 build
webpack --mode production

C:\Users\tomte\OneDrive\Documents\GitHub\H2oThermo_App-Development1\node_modules\webpack\lib\Compilation.js:4706
if (buildInfo.assets) {
^

TypeError: Cannot read properties of undefined (reading 'assets')
at Compilation.createModuleAssets (C:\Users\tomte\OneDrive\Documents\GitHub\H2oThermo_App-Development1\node_modules\webpack\lib\Compilation.js:4706:18)
at C:\Users\tomte\OneDrive\Documents\GitHub\H2oThermo_App-Development1\node_modules\webpack\lib\Compilation.js:3196:13
at Compilation._runCodeGenerationJobs (C:\Users\tomte\OneDrive\Documents\GitHub\H2oThermo_App-Development1\node_modules\webpack\lib\Compilation.js:3351:11)
at C:\Users\tomte\OneDrive\Documents\GitHub\H2oThermo_App-Development1\node_modules\webpack\lib\Compilation.js:3181:12
at C:\Users\tomte\OneDrive\Documents\GitHub\H2oThermo_App-Development1\node_modules\webpack\lib\Compilation.js:3443:6
at C:\Users\tomte\OneDrive\Documents\GitHub\H2oThermo_App-Development1\node_modules\neo-async\async.js:2818:7
at done (C:\Users\tomte\OneDrive\Documents\GitHub\H2oThermo_App-Development1\node_modules\neo-async\async.js:3522:9)
at C:\Users\tomte\OneDrive\Documents\GitHub\H2oThermo_App-Development1\node_modules\webpack\lib\Compilation.js:3404:8
at C:\Users\tomte\OneDrive\Documents\GitHub\H2oThermo_App-Development1\node_modules\webpack\lib\Compilation.js:3521:5
at C:\Users\tomte\OneDrive\Documents\GitHub\H2oThermo_App-Development1\node_modules\enhanced-resolve\lib\forEachBail.js:39:13

Node.js v18.20.2