fix: prevent getFee from returning NaN from Reporting Mode (#1401)

When using a rippled server in Reporting Mode, the server_info response does not have a load_factor property.

https://xrpl.org/rippled-server-modes.html#reporting-mode

https://github.com/ripple/rippled/issues/3812

Now, when load_factor is missing, we default to a load_factor of 1.

Fix #1398

test/mock-rippled.ts

@@ -224,6 +224,8 @@ export function createMockRippled(port) {
         }
       }
       conn.send(createResponse(request, response))
+    } else if (conn.config.reporting) {
+      conn.send(createResponse(request, fixtures.server_info.reporting))
     } else if (conn.config.returnErrorOnServerInfo) {
       conn.send(createResponse(request, fixtures.server_info.error))
     } else if (conn.config.disconnectOnServerInfo) {