message: feat(bindgen): rename js file to index.js
diff: +use std::fs;
  use console::style;
  use emoji;
  use failure::Error;
  @@ -18,6 +19,10 @@ pub fn cargo_install_wasm_bindgen() -> Result<(), Error> {
  pb.finish();
  if !output.status.success() {
  let s = String::from_utf8_lossy(&output.stderr);
  + if s.contains("already exists") {
  + PBAR.one_off_message("wasm-bindgen already installed");
  + return Ok(());
  + }
  PBAR.error("Installing wasm-bindgen failed");
  bail!(format!("Details:\n{}", s));
  } else {
  @@ -46,6 +51,9 @@ pub fn wasm_bindgen_build(path: &str, name: &str) -> Result<(), Error> {
  PBAR.error("wasm-bindgen failed to execute properly");
  bail!(format!("Details:\n{}", s));
  } else {
  + let js_file = format!("{}/pkg/{}.js", path, binary_name);
  + let index_file = format!("{}/pkg/index.js", path);
  + fs::rename(&js_file, &index_file)?;
  Ok(())
  }
  }
  