Fix crash during code editor folding and LSP

[robert-wallis]

closes #76447

Adding a bounds check on delimiter_cache which in my repro has size 1 but p_line is also 1

Repro Steps

1. open Godot
2. open script editor in Godot (important)
3. open VSCode, use and connect godot-tools to LSP
4. edit different file then step 3, add a function, delete function, save
5. crash

Tested On:

• Win 10 22H2; VSCode; godot-tools 2.0.0; 4.2.2-stable reproduce crash: ✅ (crashes with above steps)
• Win 10 22H2; VSCode; godot-tools 2.0.0; this branch: repro steps pass ✅--test success ✅
• Win 10 22H2; VSCode; godot-tools 2.0.0; (cherry picked on) Godot 4.2.2 15073af: repro steps pass ✅--test success ✅
• MacOS 14.5 Intel: VSCode; godot-tools 2.0.0; 4.2.2-stable reproduce crash: ❌ (doesn't crash)
• MacOS 14.5 Intel; VSCode; godot-tools 2.0.0; this branch: repro steps pass ✅ --test success ✅
• MacOS 14.5 Intel; VSCode; godot-tools 2.0.0; (cherry picked on) Godot 4.2.2 15073af: repro steps pass ✅ --test success ✅

[akien-mga]

Seems good as a stop-gap measure for a crash that seems to affect a lot of users.

But as pointed out in the bug report the bug is likely deeper, and would be worth looking into. CC @Paulb23 @kitbdev

I'm not even sure why CodeEdit is involved at all for users using external editors with LSP.

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉