Bug report

Using null coalescing operator in the expression wrongly makes the first operand not-nullable, see type change between lines 7-10 and no type change between lines 5-7.

The false positive occurs when using something like:

$routeParams = $request?->attributes->get('_route_params', []) ?? [];

and don't occur when using:

$routeParams = $request?->attributes->get('_route_params', []);

Code snippet that reproduces the problem

https://phpstan.org/r/e71669b3-f8e3-43e9-bf54-08d6fd2bb9fd

Expected output

Reading a nullable value shouldn't make it not-nullable even when null coalescing operator is used.