Create an http client with axios and Typescript

http.ts

import axios, { AxiosInstance, AxiosRequestConfig } from 'axios'

const headers: Readonly<Record<string, string | boolean>> = {
  Accept: 'application/json',
  'Content-Type': 'application/json; charset=utf-8',
  'X-Requested-With': 'XMLHttpRequest'
}

class Http {
  private instance: AxiosInstance | null = null

  private get http(): AxiosInstance {
    return this.instance != null ? this.instance : this.initHttp()
  }

  initHttp() {
    const http = axios.create({
      baseURL: process.env.NEXT_PUBLIC_API_BASEURL,
      timeout: 10000,
      headers
    })

    http.interceptors.response.use(
      response => response.data.result,
      error => {
        let resolvedError: Record<string, unknown> | string

        if (error.response) {
          /*
           * The request was made and the server responded with a
           * status code that falls out of the range of 2xx
           */
          resolvedError =
            error.response.data.errors?.errors ??
            error.response.data.errors?.message
        } else if (error.request) {
          /*
           * The request was made but no response was received, `error.request`
           * is an instance of XMLHttpRequest in the browser and an instance
           * of http.ClientRequest in Node.js
           */
          resolvedError = 'Server not Responding'
        } else {
          // Something happened in setting up the request and triggered an Error
          resolvedError = error.message
        }

        return Promise.reject(resolvedError)
      }
    )

    this.instance = http
    return http
  }

  request<T, R = T>(config: AxiosRequestConfig): Promise<R> {
    return this.http.request(config)
  }

  get<T, R = T>(url: string, config?: AxiosRequestConfig): Promise<R> {
    return this.http.get<T, R>(url, config)
  }

  post<T, R = T>(
    url: string,
    data?: T,
    config?: AxiosRequestConfig
  ): Promise<R> {
    return this.http.post<T, R>(url, data, config)
  }

  put<T, R = T>(
    url: string,
    data?: T,
    config?: AxiosRequestConfig
  ): Promise<R> {
    return this.http.put<T, R>(url, data, config)
  }

  delete<T, R = T>(url: string, config?: AxiosRequestConfig): Promise<R> {
    return this.http.delete<T, R>(url, config)
  }
}

export const http = new Http()