Steps required to reproduce the problem

1. Start with a project using phpstan/phpstan 1.10.48, phpstan/phpstan-phpunit 1.13.15, phpspec/prophecy dev-master, phpspec-prophecy-phpunit dev-master, and some tests using Prophecy like (new Prophet())->prophesize(Some::class)
2. Upgrade phpspec/prophecy to 1.18 (from dev-master)

Expected Result

• PHPStan finished without internal errors

Actual Result

• PHPStan runs into an internal error

Xdebug analysis shows that the difference before/after is in ProphesizeDynamicReturnTypeExtension::getTypeFromMethodCall line 70 where the $returnType instanceof check used to be true but is not anymore:

• before: GenericObjectType
• after: ConditionalTypeForParameter