"Getting Started": build-app gives "Failed to find esbuild"

Following the steps in the Getting Started guide gives the following output when reaching the section "Creating Executables":

$ spago build-app
[info] Build succeeded.
[error] Failed to find esbuild. See https://esbuild.github.io/getting-started/#install-esbuild for ways to install esbuild.

purs version 0.15.4 and spago 0.20.9, node 16.13.0 and npm 8.19.2, ubuntu 20 on x86.

Steps to reproduce:

mkdir my-project
cd my-project
spago init
spago install lists foldable-traversable

cat << EOF > src/Euler.purs
module Euler where

import Prelude

import Data.List (range, filter)
import Data.Foldable (sum)

ns = range 0 999

multiples = filter (\n -> mod n 3 == 0 || mod n 5 == 0) ns

answer = sum multiples
EOF

cat << EOF > src/Main.purs
module Main where

import Prelude

import Euler (answer)
import Effect.Console (log)

main = do
  log ("The answer is " <> show answer)
EOF

spago build
spago bundle-app

Start with the Getting Started guide's "Creating Executables" section and reproduce the documented spago build-app command using the commands and versions listed in the issue. Check the esbuild installation guidance linked in the error. Done means the documented steps no longer produce "Failed to find esbuild", or the guide clearly explains the required installation step.