fix: Return proper error objects for HTTP errors

web3.js/src/connection.js

@@ -509,7 +509,11 @@ function createRpcRequest(url): RpcRequest {
     try {
       const res = await fetch(url, options);
       const text = await res.text();
-      callback(null, text);
+      if (res.ok) {
+        callback(null, text);
+      } else {
+        callback(new Error(`${res.status} ${res.statusText}: ${text}`));
+      }
     } catch (err) {
       callback(err);
     }

web3.js/test/__mocks__/node-fetch.js

@@ -74,6 +74,9 @@ const mock: JestMockFn<any, any> = jest.fn((fetchUrl, fetchOptions) => {
     mockResponse,
   );
   return {
+    ok: true,
+    status: 200,
+    statusText: 'OK',
     text: () => {
       return Promise.resolve(JSON.stringify(response));
     },