Using constant Typed Dictionary in _export_file in EditorExportPlugin crashes the engine

### Tested versions

Does not work in 4.4-dev4, 4.4-dev6

### System information

Godot v4.4.dev6 - Windows 10.0.19045 - Single-window, 1 monitor - OpenGL 3 (Compatibility) - NVIDIA GeForce RTX 4050 Laptop GPU (NVIDIA; 32.0.15.6070) - 13th Gen Intel(R) Core(TM) i5-13500HX (20 threads)

### Issue description

Crashes
```gdscript
func _export_file(path: String, type: String, features: PackedStringArray) -> void:
const EXCLUDED_DIRECTORIES: Dictionary[String, PackedStringArray] = {
"testt": [
"res://testfolder",
]
}

for feature: String in features:
if EXCLUDED_DIRECTORIES.has(feature):
for directory: String in EXCLUDED_DIRECTORIES[feature]:
print(path)
# Skip files inside of this directory
if path.begins_with(directory): skip()
```

Does not crash (same as above but var instead of const)
```gdscript
func _export_file(path: String, type: String, features: PackedStringArray) -> void:
var EXCLUDED_DIRECTORIES: Dictionary[String, PackedStringArray] = {
"testt": [
"res://testfolder",
]
}

for feature: String in features:
if EXCLUDED_DIRECTORIES.has(feature):
for directory: String in EXCLUDED_DIRECTORIES[feature]:
print(path)
# Skip files inside of this directory
if path.begins_with(directory): skip()
```

Does not crash
```gdscript
func _export_file(path: String, type: String, features: PackedStringArray) -> void:
const EXCLUDED_DIRECTORIES: Dictionary = {
"testt": [
"res://testfolder",
]
}

for feature: String in features:
if EXCLUDED_DIRECTORIES.has(feature):
for directory: String in EXCLUDED_DIRECTORIES[feature]:
print(path)
# Skip files inside of this directory
if path.begins_with(directory): skip()
```

### Steps to reproduce

Use a Typed dictionary marked with `const` instead of `var` in _export_file of an EditorExportPlugin, then export the project

### Minimal reproduction project (MRP)

[New Compressed (zipped) Folder.zip](https://github.com/user-attachments/files/18145537/New.Compressed.zipped.Folder.zip)

Start by reproducing the crash with the provided minimal project, using a typed Dictionary marked const inside EditorExportPlugin._export_file. Compare the const and var cases during project export, then verify that the typed-constant case no longer crashes while the existing untyped-constant and var cases remain functional.

Written by the indexing model from the issue text.