Compiler does not properly delete native FFI src code from build output if the src has been deleted

[Acepie]

See https://github.com/gleam-lang/gleam/issues/1970 for more context. If I create a method with FFI like the externals example from the tour and run the code in a new project

import gleam/io

// A type with no Gleam constructors
pub type DateTime

// An external function that creates an instance of the type
@external(javascript, "./my_package_ffi.mjs", "now")
fn now() -> DateTime

// The `now` function in `./my_package_ffi.mjs` looks like this:
// export function now() {
//   return new Date();
// }

pub fn main() {
  io.debug(now())
}

gleam run

Then it runs as expected. If I then delete ./my_package_ffi.mjs from the src directory and then do another run, it continues to run. Despite the original src no longer being present. Only after a gleam clean does the run fail with a module not found error like expected. This is the case with both erlang and javascript. I believe this is because the compiler is simply doing a raw copy of the src files that have changed but is not checking if there are build files that should not be present so the old copy is still present.

[lpil]

Aye. Duplicate of https://github.com/gleam-lang/gleam/issues/1970

[lpil]

Splitting it out to have generate the non-generated be different.