LSP panic (exit code 101) on startup with Django custom User model — answers_solver.rs:233 unwrap() on None

## Environment

| Item | Version |
|------|---------|
| OS | macOS 26.3 (arm64) |
| Python | 3.14.2 |
| Pyrefly | 0.53.0 |
| VS Code | 1.109.5 |
| VS Code Extension | meta.pyrefly-0.53.0-darwin-arm64 |
| Django | 6.0.2 |
| django-stubs | 5.2.9 |

## Reproducible file

`src/core/models.py` — Django custom User model with email-based auth:

```python
"""Custom User model using email as the login identifier instead of username."""

from typing import Any, ClassVar

from django.contrib.auth.base_user import (
    AbstractBaseUser,
    BaseUserManager,
)
from django.contrib.auth.models import PermissionsMixin
from django.db.models import BooleanField, CharField, EmailField


class UserManagement(BaseUserManager["User"]):
    def create_user(
        self, email: str, password: str | None = None, **extra_fields: Any
    ) -> "User":
        if not email:
            raise ValueError("Users must have an email address")
        user: User = self.model(email=self.normalize_email(email), **extra_fields)
        user.set_password(password)
        user.save(using=self._db)
        return user

    def create_superuser(self, email: str, password: str) -> "User":
        user: User = self.create_user(email=email, password=password)
        user.is_staff = True
        user.is_superuser = True
        user.save(using=self._db)
        return user


class User(AbstractBaseUser, PermissionsMixin):
    email = EmailField(max_length=255, unique=True)
    name = CharField(max_length=255)
    is_active = BooleanField(default=True)  # type: ignore[bad-override]
    is_staff = BooleanField(default=False)

    objects: ClassVar[UserManagement] = UserManagement()

    USERNAME_FIELD = "email"
```

## What happens

Opening this file in VS Code causes the Pyrefly LSP to panic immediately during the initial indexing phase (`DidOpenTextDocument`). The server crashes 5 times and stops restarting.

## Crash log

```
starting generic LSP server
 INFO Reading messages
 INFO File src/core/models.py opened, prepare to validate open files.
 INFO Ran task on sourcedb_queue heavy task queue. Queue time: 0.00, task time: 0.00
 INFO Published 0 diagnostics for file:///…/src/core/models.py
 INFO Validated open files and committed transaction.
 INFO Cleared 1 dropped configs from config cache
 INFO Language server processed event `DidOpenTextDocument` in 1.21s (0.00s waiting)
 WARN /var/folders/…/pyrefly_bundled_typeshed_e52a9c11f401/pyrefly.toml: Cannot use both `permissive-ignores` and `enabled-ignores`: `permissive-ignores` will be ignored.
 INFO Unhandled notification: Notification { method: "$/setTrace", params: Object {"value": String("off")}, activity_key: None }
[Error] Client Pyrefly language server: connection to server is erroring.
write EPIPE
ERROR Thread panicked, shutting down: panicked at pyrefly/lib/alt/answers_solver.rs:233:66:
called `Option::unwrap()` on a `None` value
Backtrace:
   0: <std::backtrace::Backtrace>::create
   1: <std::sync::once::Once>::call_once::<pyrefly_util::panic::print_panic::{closure#0}>::{closure#0}
   2: <std::sys::sync::once::queue::Once>::call
   3: pyrefly_util::panic::print_panic
   4: pyrefly_util::panic::exit_on_panic::{closure#0}
   5: std::panicking::panic_with_hook
   6: std::panicking::panic_handler::{closure#0}
   7: std::sys::backtrace::__rust_end_short_backtrace::<std::panicking::panic_handler::{closure#0}, !>
   8: __rustc::rust_begin_unwind
   9: core::panicking::panic_fmt
  10: core::panicking::panic
  11: core::option::unwrap_failed
  12: <pyrefly::alt::answers_solver::AnswersSolver<pyrefly::state::state::TransactionHandle>>::get_idx::<pyrefly::binding::binding::KeyClassField>
  13: <pyrefly::alt::answers_solver::AnswersSolver<pyrefly::state::state::TransactionHandle>>::get_from_module::<pyrefly::binding::binding::KeyClassField>
  14: <pyrefly::alt::answers_solver::AnswersSolver<pyrefly::state::state::TransactionHandle>>::get_non_synthesized_field_from_current_class_only
  15: <pyrefly::alt::answers_solver::AnswersSolver<pyrefly::state::state::TransactionHandle>>::get_class_member_with_defining_class
  16: <pyrefly::state::steps::Step>::step_solutions::<pyrefly::state::state::TransactionHandle>
  17: <pyrefly::state::steps::Step>::compute::<pyrefly::state::state::TransactionHandle>
  18: <pyrefly::state::state::Transaction>::demand
  19: <pyrefly::state::state::Transaction>::run_step::{closure#1}
  20: <rayon_core::job::HeapJob<…> as rayon_core::job::Job>::execute
  21: <rayon_core::registry::WorkerThread>::wait_until_cold
  22: std::sys::backtrace::__rust_end_short_backtrace::<…>
  23: <std::thread::lifecycle::spawn_unchecked<…>>::call_once::{shim:vtable#0}
  24: <std::sys::thread::unix::Thread>::new::thread_start
  25: __pthread_cond_wait

PANIC Sorry, Pyrefly crashed, this is always a bug in Pyrefly itself.
PANIC Please report the bug at https://github.com/facebook/pyrefly/issues/new
[Error] Server process exited with code 101.
[Error] The Pyrefly language server server crashed 5 times in the last 3 minutes. The server will not be restarted.
```

## Additional notes

- The panic happens during `DidOpenTextDocument` processing, before any interactive LSP requests (no `codeAction`, `documentSymbol` etc.)
- The `write EPIPE` on the Node.js side is a **consequence** of the Rust thread panic closing the pipe, not a separate cause
- The bundled `pyrefly.toml` warning (`Cannot use both permissive-ignores and enabled-ignores`) appears on every startup — possible related config issue in the bundled typeshed
- Pyrefly CLI (`pyrefly check`) works fine on the same file — crash is LSP-only
- Related closed issue: #2238 (same Django + exit 101 symptoms, closed for lack of repro)
- Crash location (`answers_solver.rs:233`) is different from the previously fixed Django panic in #1527 (`answers_solver.rs:650`)

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LSP panic (exit code 101) on startup with Django custom User model — answers_solver.rs:233 unwrap() on None #2479

Environment

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Development

Item	Version
OS	macOS 26.3 (arm64)
Python	3.14.2
Pyrefly	0.53.0
VS Code	1.109.5
VS Code Extension	meta.pyrefly-0.53.0-darwin-arm64
Django	6.0.2
django-stubs	5.2.9

LSP panic (exit code 101) on startup with Django custom User model — answers_solver.rs:233 unwrap() on None #2479

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