Correcting SPFx gulp –ship Uglify Errors: Unexpected token: punc (()

We came across the following problem when trying to execute a gulp --ship on out SPFx development


[15:03:34] Starting subtask 'webpack'...
[15:03:49] Error - [webpack] 'dist':
list-view-demo-webpart-web-part.js from UglifyJs
Unexpected token: punc (() [list-view-demo-webpart-web-part.js:962,7]

In researching this issue it turns out that this issue stems from a problem with the webpack uglify plugin (uglify-webpack-plugin) which historically does not work with ES6 code.

From what I read, it seems like the current SPFx 1.8 does use the correct version of webpack and the uglify plugin to avoid this issue but it was still coming up.

We solved the issue by implementing a suggestion to a related issue on github

https://github.com/SharePoint/sp-dev-docs/issues/2782

The key was presented in one of the responses to the issue

https://github.com/SharePoint/sp-dev-docs/issues/2782#issuecomment-475519680

By replacing the uglify plugin with the terser plugin for webpack, the issue was resolved and we were able to Build and deploy.

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