Error when transforming a counting rule in a correlation rule

[VincentD06]

Step to reproduce :

• Create a count rule
• Clic on 'Modifier' on this rule
• In the tree, clic on 'Ensuite'

Problem :
The loading spinner is present in the additionnal stream and an error message is present in the console of the browser.

Investigation :
On update, the second stream is null and it is not initialized when component is loaded.

[frantz45]

The easiest way to fix it is to disallow to change into an incompatible rule type.