Before you investigate further, i figuered out, that this issue has been caused by a npm related error, where it ignored the version and installed an old one.

After fixing up NPM and updating it works :)

I have installed the MDB UI Kit via NPM. I am also using Webpack and Typescript. Main Import is done in the index.ts file:

import * as mdb from "mdb-ui-kit";  or `import "mdb-ui-kit/js/mdb.min.js";`

Then I try to import it in another ts file

import { Input, initMDB } from "mdb-ui-kit";
initMDB({ Input });

When the function tries to execute, the above mentioned error occurs. On the other hand importing Modals does work, so i don't know if i caused the issue.

import { Modal } from "mdb-ui-kit";
let modalExec = document.getElementById("anyHtmlModal");
mdbModal = new Modal(modalExec); //This does work within my application :)

In what situation do you encounter this error and how are you doing your imports?