Dropping an RDFGraph when there is a non-RDFGraph rel table leaves the rel table "dangling"

[semihsalihoglu-uw]

Consider an RDFGraph UniKG and another node table Students and a rel table SameAs from Students to UniKG_r. You can drop UniKG even if that would leave Students around. Normally this would give a Binder exception that says: "Cannot delete node table nodeTableX referenced by rel table relTableY."

To replicate:

kuzu> CREATE RDF Graph UniKG;
kuzu> CREATE NODE TABLE Students(name STRING, primary key (name));
kuzu> CREATE REL TABLE SameStudent(FROM Students TO UniKG_r);
kuzu> DROP TABLE UniKG;
kuzu>  MATCH (a:Students)-[s:SameStudent]->(b) RETURN *;
Error: unordered_map::at: key not found

Normally, this would happen:

kuzu> CREATE NODE TABLE nodeTable1 (name STRING, primary key (name));
kuzu> CREATE NODE TABLE nodeTable2 (name STRING, primary key (name));
kuzu> CREATE REL TABLE relTable (FROM nodeTable1 TO nodeTable2);
kuzu> DROP TABLE nodeTable2;
Error: Binder exception: Cannot delete node table nodeTable2 referenced by rel table relTable.

So the system does not allow dropping nodeTable2.

[andyfengHKU]

Fixed in PR #2760