PBJS Core: call custom render func after loadscript if provided (prebid#6422)

Author: jeremiegirault

src/Renderer.js

@@ -39,17 +39,22 @@ export function Renderer(options) {
 
   // use a function, not an arrow, in order to be able to pass "arguments" through
   this.render = function () {
+    const renderArgs = arguments
+    const runRender = () => {
+      if (this._render) {
+        this._render.apply(this, renderArgs)
+      } else {
+        utils.logWarn(`No render function was provided, please use .setRender on the renderer`);
+      }
+    }
+
     if (!isRendererPreferredFromAdUnit(adUnitCode)) {
       // we expect to load a renderer url once only so cache the request to load script
+      this.cmd.unshift(runRender) // should render run first ?
       loadExternalScript(url, moduleCode, this.callback);
     } else {
       utils.logWarn(`External Js not loaded by Renderer since renderer url and callback is already defined on adUnit ${adUnitCode}`);
-    }
-
-    if (this._render) {
-      this._render.apply(this, arguments) // _render is expected to use push as appropriate
-    } else {
-      utils.logWarn(`No render function was provided, please use .setRender on the renderer`);
+      runRender()
     }
   }.bind(this) // bind the function to this object to avoid 'this' errors
 }