Fix bug in CorrelatedSubqueryUnnestSolver (#4088)

* Fix issue 4080

* Run clang-format

---------

Co-authored-by: CI Bot <andyfengHKU@users.noreply.github.com>

src/optimizer/correlated_subquery_unnest_solver.cpp

@@ -1,7 +1,9 @@
 #include "optimizer/correlated_subquery_unnest_solver.h"
 
+#include "common/exception/internal.h"
 #include "planner/operator/logical_hash_join.h"
 #include "planner/operator/scan/logical_expressions_scan.h"
+
 using namespace kuzu::planner;
 
 namespace kuzu {
@@ -30,13 +32,18 @@ void CorrelatedSubqueryUnnestSolver::solveAccHashJoin(LogicalOperator* op) const
     auto acc = op->getChild(0).get();
     auto rightSolver = std::make_unique<CorrelatedSubqueryUnnestSolver>(acc);
     rightSolver->solve(hashJoin.getChild(1).get());
-    auto leftSolver = std::make_unique<CorrelatedSubqueryUnnestSolver>(nullptr);
+    auto leftSolver = std::make_unique<CorrelatedSubqueryUnnestSolver>(accumulateOp);
     leftSolver->solve(acc->getChild(0).get());
 }
 
 void CorrelatedSubqueryUnnestSolver::visitExpressionsScan(LogicalOperator* op) {
     auto expressionsScan = op->ptrCast<LogicalExpressionsScan>();
-    KU_ASSERT(accumulateOp != nullptr);
+    // LCOV_EXCL_START
+    if (accumulateOp == nullptr) {
+        throw common::InternalException(
+            "Failed to execute CorrelatedSubqueryUnnestSolver. This should not happen.");
+    }
+    // LCOV_EXCL_STOP
     expressionsScan->setOuterAccumulate(accumulateOp);
 }
 

test/test_files/issue/issue.test

@@ -2,6 +2,25 @@
 
 --
 
+-CASE 4080
+-STATEMENT CREATE NODE TABLE V(id INT, PRIMARY KEY(id));
+---- ok
+-STATEMENT CREATE REL TABLE links_to(FROM V to V);
+---- ok
+-STATEMENT CREATE REL TABLE parent(FROM V to V);
+---- ok
+-STATEMENT CREATE (:V {id: 1}), (:V {id: 2});
+---- ok
+-STATEMENT MATCH (v1:V {id: 1}), (v2:V {id: 2})
+           CREATE (v1)-[:links_to]->(v2), (v1)-[:parent]->(v2)
+---- ok
+-STATEMENT WITH 2 as parent_id
+           OPTIONAL MATCH (v1:V)-[:links_to*1..]->(:V)
+           WHERE EXISTS {MATCH (v1)-[:parent]->(:V {id: parent_id})}
+            RETURN v1.id;
+---- 1
+1
+
 -CASE listContainsCast
 -STATEMENT CREATE NODE TABLE A(id SERIAL, primary key(id));
 ---- ok