ClipboardEvent undefined in IE11
It seems to be an issue in IE with angulars JIT (Just-In-Time compilation) build mode. It helped to use AOT (Ahead-Of-Time). Then there's no error loading the site.
ng build --aot
JIT makes the browser compile the code on runtime and IE seems to not compile correctly (that's guessing!).
Here's the explaination of difference bewteen AOT and JIT:
https://angular.io/guide/aot-compiler
Note:
Paste from clipboard does still not work in IE, though. Here is well explained why it's not working everywhere: Clipboard Event (Stack Overflow)