/**
 * Sends a GET request to a specified URL with optional query parameters, optional Bearer Token, and optional custom headers.
 * The 'Content-Type' header is set to 'application/json' by default, but can be overridden or supplemented by the provided headers parameter.
 * This function returns the response data as a JSON object of type U if the request is successful.
 * If the response status is an unsuccessful request or a faulty response), an error is thrown with relevant information.
 *
 * @template T - The type of the query parameters.
 * @template U - The expected type of the response data.
 *
 * @param url - The URL to send the GET request to.
 * @param params - Optional query parameters to be appended to the URL. Must match the structure defined by type T.
 * @param token - Optional token to be included in the Authorization header as a Bearer token.
 * @param headers - Optional headers to be included in the request. Allows overriding the default 'Content-Type' header and providing additional headers. Should be an object with keys and values representing header names and their values.
 *
 * @returns A Promise that resolves to the JSON-parsed response body of the GET request of type U.
 *
 * @example
 * ```typescript
 * // e.g. Get UserResponse data
 * // Query Parameters
 * interface QueryParams {
 *  userId: string
 * }
 *
 * // Response
 * interface UserResponse {
 *  id: number
 *  name: string
 *  email: string
 * }
 *
 * async function fetchUserData() {
 *   const url = 'https://api.example.com/user';
 *   const queryParams: QueryParams = { userId: '123' };
 *   try {
 *     const userData = await sendGet<QueryParams, UserResponse>(
 *       url,
 *       queryParams,
 *       'mytoken123'
 *     );
 *     console.log(userData); // { id: 123, name: 'Kawasaki', email: 'test@example.com' }
 *   } catch (error) {
 *     console.error("Failed to fetch user data:", error);
 *   }
 * }
 * ```
 *
 * @throws Will throw an error if the GET request fails or if the response status is not a valid number, indicating a failure or a faulty response.
 */
export declare const sendGet: <T = Record<string, never>, U = any>(url: string, params?: T, token?: string, headers?: Record<string, string>) => Promise<U>;