fix(emotion): Fix panic on function name identifier being None

[Codex-]

Follow up to #245

Fixes this panic by ensuring that there is something to unwrap:

thread '<unnamed>' panicked at 'called `Option::unwrap()` on a `None` value', /home/runner/work/plugins/plugins/packages/emotion/transform/src/lib.rs:449:48
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
thread '<unnamed>' panicked at /Users/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/swc-0.270.26/src/plugin.rs:162:14:
failed to invoke plugin: failed to invoke plugin on 'Some("/Users/alexmiller/dev/app/node_modules/jest-runner/build/index.js")'

Caused by:
    0: failed to invoke `@swc/plugin-emotion` as js transform plugin at @swc/plugin-emotion
    1: RuntimeError: unreachable

Stack backtrace:
   0: _napi_register_module_v1
   1: _wasmer_vm_imported_memory32_atomic_notify
   2: _napi_register_module_v1
   3: _napi_register_module_v1
   4: _napi_register_module_v1
   5: _napi_register_module_v1
   6: _napi_register_module_v1

[changeset-bot]

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[kdy1]

Thank you!