fix(request): set GET as default request method

Defaults request method to "GET" to avoid setting the "Content-Type" to json for requests where method is omitted.

PR: #50 

Resolves: #49

src/__tests__/request.spec.ts

@@ -58,6 +58,19 @@ describe('request', () => {
             );
         });
 
+        it('calls should not send "application/json", if method is not passed', async () => {
+            await request(TEST_URL);
+
+            expect(getMockFetch()).toHaveBeenCalledTimes(1);
+            expect(getMockFetch()).toHaveBeenCalledWith(
+                TEST_URL,
+                expect.objectContaining({
+                    credentials: 'same-origin',
+                    headers: {},
+                })
+            );
+        });
+
         it('calls fetch and respects overrides in options', async () => {
             await request(TEST_URL, {credentials: 'omit'});
 

src/request.ts

@@ -37,7 +37,7 @@ const _tryParseJSON = (res: Response): Promise<any> => {
  */
 export const _fetchJSON = (
     url: string,
-    {headers, method, mode, ...options}: RequestInit = {}
+    {headers = {}, method = 'GET', mode, ...options}: RequestInit = {}
 ): Promise<{}> => {
     let fetchHeaders = headers as HeadersInit;