react-split-pane | React split-pane component | Frontend Framework library

My title component is not getting styled by its css file. I want it to have a green background. It is coming up white for some reason.

Here is the Component Js file:

I'm getting the error at line 116

For my new react project I need a split pane.
I am using https://github.com/tomkp/react-split-pane for this.
After I implemented everything, I wanted to my header above so it would look like this.

So I added the header to my root component.

I am trying to solve that error and I spent hours trying to fix it. I updated all my dependencies from a project that used material-ui , so I migrated to @material-ui/core because the first is deprecated. I have a copy of that project (No code changes) and in the non-updated project I don't get the error.

When I updated everything I got the follow error:

Error: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.

Here is my class:

I have a simple app that I was planning to deploy to Heroku. It works on localhost, but when do git push heroku master I get an error saying that need an appropriate loader to handle this file type, currently no loaders are configured to process this file. I also tried to change <> to

When trying to run some simple edition of Microsoft Typescript-React starter tutorial: https://github.com/Microsoft/TypeScript-React-Starter I'm getting the following error over an imported module:

(31,30): JSX element type 'SplitPane' does not have any construct or call signatures.

I have checked online, and there are a couple of questions with my same error: What does the error "JSX element type '...' does not have any construct or call signatures" mean? & https://github.com/Microsoft/TypeScript/issues/28631 but they don't help me to understand where my error is, since I am using an external module.

To make it clearer I'll add some code. I am using the same files as are outputed when using npx create-react-app my-app --scripts-version=react-scripts-ts, and just edited package.json, and created SplittedPane.tsx.

This is the file SplittedPane.tsx:

I just installed react-split-pane in my application, but it does not seem to work.

I'm using react-split-pane version 0.1.68 but I tested it with 0.1.66 and 0.1.64 as well.

This is my component:

I'm new to react so I hope the questions isn't too stupid.

In short: I want to use a certain Component inside another components props. But it isn't working like desired.

I want to use Material UI Cards in following Component: Link to repo of "Material-UI Tree View"

For testing I wrote following code:

I am getting a blank browser and in console I get this error of

Uncaught TypeError: Super expression must either be null or a function, not undefined

I have read other similar posts but did not see anything relevant.

This is my webpack.config.js file: