fix: drop JSONExtract chains iteratively

The Databricks parser builds a v:a:a:… path in a loop, one JSONExtract per
link, each holding the previous one as its input. JSONExtract was missing
from the iterative drop list, so freeing a long path recursed once per link:
on a 2 MiB thread, SELECT v:a:a:… FROM t aborted with a stack overflow from
about 20,000 links in debug and 50,000 in release, including after the parser
had refused the tree for depth.

JSONExtract now frees its descendants with the worklist, like JsonExtractFunc
and the other loop-built nodes, and the 100,000-step drop test covers it.

Author: kvlonge

crates/sqlquack-syntax/src/expressions/tree/_helpers/drops.rs

@@ -1,6 +1,7 @@
-//! Iterative drops for nodes a parser chains in a loop, such as `x::INT::INT`, `v[1][1]` or `q |> WHERE a |> WHERE b`.
+//! Iterative drops for nodes a parser chains in a loop, such as `x::INT::INT`, `v[1][1]`, `v:a:a` or `q |> WHERE a |> WHERE b`.
 
 use crate::expressions::functions::models::JSONCast;
+use crate::expressions::functions::models::JSONExtract;
 use crate::expressions::functions::models::Operator;
 use crate::expressions::functions::models::Xor;
 use crate::expressions::operators::models::Alias;
@@ -62,6 +63,7 @@ drop_iteratively!(
     IsNull,
     IsTrueFalse,
     JSONCast,
+    JSONExtract,
     JsonExtractFunc,
     LikeOp,
     MatchRecognize,

crates/sqlquack-syntax/src/guard/tests/test_ast_guard.rs

@@ -1,4 +1,5 @@
 use crate::expressions::functions::models::JSONCast;
+use crate::expressions::functions::models::JSONExtract;
 use crate::expressions::functions::models::Operator;
 use crate::expressions::functions::models::Xor;
 use crate::expressions::names::models::Identifier;
@@ -424,6 +425,24 @@ fn given_a_100_000_step_chain_of_a_node_parsers_build_in_a_loop_when_dropping_on
             },
             expected_depth: 100_000,
         },
+        ChainStepTestCase {
+            description: "Databricks v:a:a paths",
+            step: |input| {
+                Expression::JSONExtract(Box::new(JSONExtract {
+                    this: Box::new(input),
+                    expression: Box::new(Expression::number(1)),
+                    only_json_types: None,
+                    expressions: Vec::new(),
+                    variant_extract: None,
+                    json_query: None,
+                    option: None,
+                    quote: None,
+                    on_condition: None,
+                    requires_json: None,
+                }))
+            },
+            expected_depth: 100_000,
+        },
         ChainStepTestCase {
             description: "array slices",
             step: |input| {