Bug: CEF "This site can't be reached" when HTML not available

[MauriceVeraart]

Observed Behavior

With the latest CEF update the HTML producer now gives a big white screen with
"This site can’t be reached
<someip || host>:8080/templatename.html refused to connect."
when a HTML does not exist or cannot be found,
this is logic behaviour in standard browser context that "sneaked in"
but in the earlier version it just gave nothing which is better behaviour in CasparCG context.

Expected behaviour

Expected behaviour is producing a empty layer when a HTML can not be found

Steps to reproduce

3. ...

Environment

• Commit: [e.g. ab1234c]
• Server version: [e.g. v2.2]
• Operating system: [e.g. Windows 10]