Catch Handler

[mlmoravek]

Reason (Why?)
Currently no error will be shown to the user if an ajax request failed.

Solution (What?)
Add catch handler to loadPosts function and show a error message to the user

Acceptance criteria
The User will see if when no data could be loaded.

[mhendlich]

Axios supports global interceptors(middleware) that can be used for this.
Example from another codebase:

axiosInstance.interceptors.response.use(
    res => res,
    err => {
        const status = err?.response?.status

        if (status === 400 || status === 500) {
            const data = err.response.data

            if (typeof data === 'object' && data.message) {
                const text = `Es ist ein Fehler aufgetreten:
      
${data.message}`

                openErrorNotification(text)
            } else if (typeof data === 'string' && data.length !== 0) {
                const text = `Es ist ein Fehler aufgetreten:
      
${data}`

                openErrorNotification(text)
            } else {
                openErrorNotification('Es ist ein Fehler aufgetreten')
            }
        }
        throw err
    },
)