Make render script use Bash best practices

package.json

@@ -5,7 +5,7 @@
 	"type": "module",
 	"scripts": {
 		"dev": "vite",
-		"build": "./render.sh",
+		"build": "./render.bash",
 		"build:targets": "yarn build:client && yarn build:server",
 		"build:client": "tsc -b && vite build --outDir dist/client",
 		"build:server": "tsc -b && vite build --outDir dist/server --ssr src/entry-server.tsx",

render.bash

@@ -1,8 +1,16 @@
-#!/bin/sh
+#!/bin/env bash
+
+set -o errexit
+set -o nounset
+set -o pipefail
+set -o xtrace
+
 yarn "build:targets"
 
 PROD='dist/prod'
+if [[ -d "$PROD" ]]; then
   rm -r "$PROD"
+fi
 mkdir -p "$PROD"
 
 echo 'Rendering webpage...'