Fix JsonRpcProvider out-of-order super call (#822).

packages/providers/src.ts/json-rpc-provider.ts

@@ -219,34 +219,32 @@ export class JsonRpcProvider extends BaseProvider {
     constructor(url?: ConnectionInfo | string, network?: Networkish) {
         logger.checkNew(new.target, JsonRpcProvider);
 
-        const getNetwork = getStatic<(network: Networkish) => Network>(new.target, "getNetwork");
+        let networkOrReady: Networkish | Promise<Network> = network;
 
-        // One parameter, but it is a network name, so swap it with the URL
+        // The network is unknown, query the JSON-RPC for it
-        if (typeof(url) === "string") {
+        if (networkOrReady == null) {
-            if (network === null) {
+            networkOrReady = new Promise((resolve, reject) => {
-                const checkNetwork = getNetwork(url);
+                setTimeout(() => {
-                network = checkNetwork;
+                    this.detectNetwork().then((network) => {
-                url = null;
+                        resolve(network);
-            }
+                    }, (error) => {
+                        reject(error);
+                    });
+                }, 0);
+            });
         }
 
-        if (network) {
+        super(networkOrReady);
-            // The network has been specified explicitly, we can use it
-            super(network);
-        } else {
-            // The network is unknown, query the JSON-RPC for it
-            super(this.detectNetwork());
-        }
 
         // Default URL
         if (!url) { url = getStatic<() => string>(this.constructor, "defaultUrl")(); }
 
         if (typeof(url) === "string") {
-            this.connection = Object.freeze({
+            defineReadOnly(this, "connection",Object.freeze({
                 url: url
-            });
+            }));
         } else {
-            this.connection = Object.freeze(shallowCopy(url));
+            defineReadOnly(this, "connection", Object.freeze(shallowCopy(url)));
         }
 
         this._nextId = 42;