chore: uniformize error messages, 80-char lines, import fmt::Display

README.md

@@ -31,9 +31,14 @@ The latest prototype is in the folder `app-proto`. It includes both a user inter
 3. Call `rustup target add wasm32-unknown-unknown` to add the [most generic 32-bit WebAssembly target](https://doc.rust-lang.org/nightly/rustc/platform-support/wasm32-unknown-unknown.html)
 4. Call `cargo install wasm-pack` to install the [WebAssembly toolchain](https://rustwasm.github.io/docs/wasm-pack/)
 5. Call `cargo install trunk` to install the [Trunk](https://trunkrs.dev/) web-build tool
+   - In the future, `trunk` can be updated with the same command. You may
+     need the `--locked` flag if your ambient version of `rustc` does not
+     match that required by `trunk`.
 6. Add the `.cargo/bin` folder in your home directory to your executable search path
    - This lets you call Trunk, and other tools installed by Cargo, without specifying their paths
    - On POSIX systems, the search path is stored in the `PATH` environment variable
+   - Alternatively, if you don't want to adjust your `PATH`, you can install
+     `trunk` in another directory `DIR` via `cargo install --root DIR trunk`
 
 ### Play with the prototype