Fix build scripts so a failure returns a nonzero exit code

.deploy/deploy.sh

@@ -1,17 +1,20 @@
 #!/bin/sh
 
+# Switch to the correct branch
 if [[ -z "${CF_PAGES_BRANCH}" ]]; then
 	git switch master || git switch -c unknown-branch
 else
 	git switch $CF_PAGES_BRANCH || git switch -c $CF_PAGES_BRANCH
 fi
 
+# Install the latest version of the Rust toolchain
 echo 🔧 Install Rust
 curl https://sh.rustup.rs -sSf | sh -s -- -y
 export PATH=$PATH:/opt/buildhome/.cargo/bin
 echo rustc version:
 rustc --version
 
+# Install the project's Node dependencies through npm
 echo 🚧 Install Node dependencies
 echo node version:
 node --version
@@ -20,9 +23,11 @@ npm --version
 cd frontend
 npm ci
 
+# Install the cargo-about Rust dependency that's used during the Webpack build process (in `vue.config.js`)
 echo 📦 Install cargo-about
 cargo install cargo-about
 
+# Build for production
 echo 👷 Build Graphite web client
 export NODE_ENV=production
 npm run build