Fix wrong assignation to intersection including ArrayAccess not being reported

[julienfalque]

Ref.: phpstan/phpstan#6184

In OffsetAccessValueAssignmentRule.php

$resultType = $arrayType->setOffsetValueType(new MixedType(), $assignedValueType);

The error is reported when $resultType is an instance of ErrorType.

In the case that works, $arrayType is a GenericObjectType and calling setOffsetValueType() on it returns an ErrorType, so the issue is reported correctly.

But in the failing case, $arrayType is an IntersectionType containing the GenericObjectType. When calling setOffsetValueType(), it will internally forward the call to the inner types, pass the results (including the ErrorType) to TypeCombinator::intersect() that returns a new IntersectionType (without ErrorType), so the issue is not reported.

I don't know the codebase very well and couldn't figure out a proper fix yet. Can someone help me please?

[julienfalque]

Issue is fixed.