Bug when defining a rule and undefining a type in the same transaction.

[krishnangovindraj]

Description

( Reported by @james-whiteside )
A null pointer exception is encountered in a schema transaction when 1. a rule is defined and 2. A type which is in the set of inferred types of some variable in the said rule is undefined.

Environment

1. TypeDB distribution: Core
2. TypeDB version: 2.26.6
3. Environment: Mac
4. Client and version: Any
5. Other details:

Reproducible Steps

1. Set up
   Define the schema (attached).

2. Execute
   Execute the following queries in the same transaction. The bug is thrown when the transaction is committed.

define
rule transitive-location:
    when {
        (location: $parent-place, located: $child-place) isa locating;
        (location: $child-place, located: $x) isa locating;
    } then {
        (location: $parent-place, located: $x) isa locating;
    };

undefine
indirect-locating sub locating;

3. Unexpected result
   A null pointer exception is thrown and the commit is aborted.

Expected result

Successfully commits the rule & undefines the type as would be if two separate transactions were used.

Additional information

TypeGraph::Statistics::outRelates(Stream<TypeVertex>) receives a null from the stream.