Legacy Vaadin vaadin.initApplication is called sometimes too early.

[johannest]

Happens at least on Vaadin 7 (7.7.14) and Vaadin 14 (14.6.8) with MPR.

Sometimes after login (pure V14 view) when the app is navigated to the main view containing some legacy content, the Vaadin 8 side initialization fails to Uncaught TypeError: vaadin.initApplication is not a function. It looks like that this vaadin.initApplication call happens right before V8 framework/VAADIN/vaadinBootstrap.js is completely loaded.

The resulting error:

Uncaught TypeError: vaadin.initApplication is not a function
at Object.eval (eval at hu (client-661F308588AD7572265EBD1D8EEA0A19.cache.js:1028), <anonymous>:3:8)
at hu (client-661F308588AD7572265EBD1D8EEA0A19.cache.js:1028)
...

Which happes after the request:

{
"syncId": 4,
"clientId": 3,
"EAGER": [
{
"url": "/framework/VAADIN/vaadinBootstrap.js",
"type": "JAVASCRIPT",
"mode": "EAGER"
}
.....
"browserDetailsUrl": "/framework",
"serviceUrl": "/framework",
"extraParams": "&ui=1"
},
"vaadin.initApplication($0, $1)"
],
[
"",
"document.title = $0"
]
]

Workaround: Add @javascript("context://framework/VAADIN/vaadinBootstrap.js"); to the V14 login view.

Proper fix would be customizing the loading of vaadinBootstrap.js such that it would be polled until really loaded and not calling vaadin.initApplication($0, $1) before.