Error compiling slint application

[SkyLeite]

When compiling a slint application, I get the following error:

slint-rust-template> error: failed to run custom build command for `slint-rust-template v0.1.0 (/build/source)`
slint-rust-template> Caused by:
slint-rust-template>   process didn't exit successfully: `/build/source/target/release/build/slint-rust-template-b344460d0da8af77/build-script-build` (exit status: 101)
slint-rust-template>   --- stderr
slint-rust-template>   error: Style fluent in not known. Use one of the builtin styles [native] or make sure your custom style is found in the include directories
slint-rust-template>   error: Cannot find requested import "std-widgets.slint" in the include search path
slint-rust-template>     --> /build/source/ui/appwindow.slint:1:37
slint-rust-template>      |
slint-rust-template>   1  | import { Button, VerticalBox } from "std-widgets.slint";
slint-rust-template>      |                                     ^
slint-rust-template>   error: Unknown type VerticalBox
slint-rust-template>     --> /build/source/ui/appwindow.slint:6:5
slint-rust-template>      |
slint-rust-template>   6  |     VerticalBox {
slint-rust-template>      |     ^
slint-rust-template>   error: Unknown type Button
slint-rust-template>     --> /build/source/ui/appwindow.slint:11:9
slint-rust-template>      |
slint-rust-template>   11 |         Button {
slint-rust-template>      |         ^
slint-rust-template>   error: 'clicked' is not a callback in <error>
slint-rust-template>     --> /build/source/ui/appwindow.slint:13:13
slint-rust-template>      |
slint-rust-template>   13 |             clicked => {
slint-rust-template>      |             ^
slint-rust-template>   thread 'main' panicked at build.rs:6:68:
slint-rust-template>   called `Result::unwrap()` on an `Err` value: CompileError(["Style fluent in not known. Use one of the builtin styles [native] or make sure your custom style is found in the include directories", "/build/source/ui/appwindow.slint:1: Cannot find requested import \"std-widgets.slint\" in the include search path", "/build/source/ui/appwindow.slint:6: Unknown type VerticalBox", "/build/source/ui/appwindow.slint:11: Unknown type Button", "/build/source/ui/appwindow.slint:13: 'clicked' is not a callback in <error>"])
slint-rust-template>   note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
slint-rust-template> warning: build failed, waiting for other jobs to finish...
slint-rust-template> [naersk] cargo returned with exit code 101, exiting
error: builder for '/nix/store/ldyyijzkpzraak49m53286pc7kihgqaw-slint-rust-template-0.1.0.drv' failed with exit code 101;
       last 10 log lines:
       >     --> /build/source/ui/appwindow.slint:13:13
       >      |
       >   13 |             clicked => {
       >      |             ^
       >
       >   thread 'main' panicked at build.rs:6:68:
       >   called `Result::unwrap()` on an `Err` value: CompileError(["Style fluent in not known. Use one of the builtin styles [native] or make sure your custom style is found in the include directories", "/build/source/ui/appwindow.slint:1: Cannot find requested import \"std-widgets.slint\" in the include search path", "/build/source/ui/appwindow.slint:6: Unknown type VerticalBox", "/build/source/ui/appwindow.slint:11: Unknown type Button", "/build/source/ui/appwindow.slint:13: 'clicked' is not a callback in <error>"])
       >   note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
       > warning: build failed, waiting for other jobs to finish...
       > [naersk] cargo returned with exit code 101, exiting
       For full logs, run 'nix log /nix/store/ldyyijzkpzraak49m53286pc7kihgqaw-slint-rust-template-0.1.0.drv'.

Here's a reproduction repository. Just run nix build -L.