fix: handle stale TID in VLE path materialization after DETACH DELETE (#2549)

[waterWang]

Fixes #2549

When a VLE path is bound via MATCH p = ... and the bound vertices are
subsequently DETACH DELETE'd, RETURN p raises an internal stale-TID
error because the VLE path materializer (build_path) lazily fetches
vertex/edge properties via heap_fetch after the underlying tuples have
been deleted.

This commit adds tolerant variants of get_vertex_entry_properties and
get_edge_entry_properties that return an empty properties object ({})
when the stored TID no longer resolves to a visible tuple, allowing
the path to be projected with the vertex present but its properties
empty.

[Copilot]

Pull request overview

This pull request fixes an internal stale TID error when projecting variable-length relationship (VLE) paths after DETACH DELETE, by making VLE path materialization tolerant of deleted tuples and returning empty properties ({}) when the stored TID is no longer visible.

Changes:

• Introduces “graceful” property accessors for vertex/edge entries that return {} instead of erroring on stale TIDs.
• Updates VLE path materialization (build_path / edge list construction) to use the graceful accessors.
• Adds a regression test and expected output to cover the MATCH p ... DETACH DELETE ... RETURN p scenario.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/include/utils/age_global_graph.h	Adds public prototypes for tolerant (“graceful”) vertex/edge property accessors.
src/backend/utils/adt/age_vle.c	Switches VLE path/edge materialization to use the graceful property accessors.
src/backend/utils/adt/age_global_graph.c	Implements graceful property accessors that return {} when heap fetch fails due to stale TIDs.
regress/sql/cypher_vle.sql	Adds a regression query reproducing Issue #2549.
regress/expected/cypher_vle.out	Adds expected output for the new regression coverage.

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