Parser: Lazily allocate hb_array_T for AST_NODE->errors

[marcoroth]

Previously, every AST node allocated an hb_array_T with a capacity of 8 for its errors array upfront, even on the happy path where no errors ever occur. This wasted 96 bytes per node (32 bytes for the hb_array_T struct + 64 bytes for the items buffer).

This pull request introduces hb_array_append_lazy, which skips the allocation entirely until the first error is actually appended. All append_*_error functions now take hb_array_T** and use lazy initialization. Parser locals are initialized as NULL instead of hb_array_init(8, ...).

I measured it against app/views/wrapped/index.html.erb in RubyEvents, which is the view that uses up the most memory in that app.

On current main eda3aa0 using ./herb parse ../rubyevents/app/views/wrapped/index.html.erb

╔════════════════════════════════════════════════════════════════════════════════════════════════════╗
║                                        ARENA MEMORY LAYOUT                                         ║
╠════════════════════════════════════════════════════════════════════════════════════════════════════╣
║  Statistics:                                                                                       ║
║    • Pages: 136                                                                                    ║
║    • Default Page Size: 16 KB                                                                      ║
║    • Total Capacity: 2.19 MB                                                                       ║
║    • Total Used: 2.06 MB                                                                           ║
║    • Total Available: 130 KB                                                                       ║
║    • Usage: 94.2%                                                                                  ║
║    • Allocations: 24894                                                                            ║
║    • Fragmentation: 126 KB                                                                         ║
║      (5.7% skipped in non-tail pages)                                                              ║
╚════════════════════════════════════════════════════════════════════════════════════════════════════╝

Compared to this pull request:

╔════════════════════════════════════════════════════════════════════════════════════════════════════╗
║                                        ARENA MEMORY LAYOUT                                         ║
╠════════════════════════════════════════════════════════════════════════════════════════════════════╣
║  Statistics:                                                                                       ║
║    • Pages: 125                                                                                    ║
║    • Default Page Size: 16 KB                                                                      ║
║    • Total Capacity: 2.02 MB                                                                       ║
║    • Total Used: 1.92 MB                                                                           ║
║    • Total Available: 106 KB                                                                       ║
║    • Usage: 94.9%                                                                                  ║
║    • Allocations: 21459                                                                            ║
║    • Fragmentation: 103 KB                                                                         ║
║      (5.0% skipped in non-tail pages)                                                              ║
╚════════════════════════════════════════════════════════════════════════════════════════════════════╝

Total arena used:  2.06 MB   → 1.92 MB  (−140 KB)
Allocations:        24,894   → 21,459   (−3,435)
Fragmentation:      126 KB   → 103 KB   (−23 KB)

I think this is kind of nice improvement for just changing the way error arrays are initialized. There is probably more we can do in the same realm.

Resolves #1343
Related: #1381

[pkg-pr-new]

npx https://pkg.pr.new/@herb-tools/formatter@1425

npx https://pkg.pr.new/@herb-tools/language-server@1425

npx https://pkg.pr.new/@herb-tools/linter@1425

commit: 406f72c

[github-actions]

🌿 Interactive Playground and Documentation Preview

A preview deployment has been built for this pull request. Try out the changes live in the interactive playground:

• Playground Preview
• Documentation Preview
• Website Preview

---

_{🌱 Grown from commit 406f72c}