Install Hadoop 2.7.3 via brew

brew_install_hadoop_2.7.3.sh

#!/usr/bin/env bash

BREW_PREFIX=$(brew --prefix);

# abort if already installed, else continue
if ! grep -q hadoop <(brew list); then
  # unlink broken installation attempts
  brew unlink hadoop > /dev/null 2>&1;

  # install hadoop 2.7.3
  # expect benign errors
  brew install https://raw.githubusercontent.com/Homebrew/homebrew-core/7a4dabfc1a2acd9f01a1670fde4f0094c4fb6ffa/Formula/hadoop.rb;

  # retain backup of default configs
  cp -R ${BREW_PREFIX}/Cellar/hadoop/2.7.3/libexec/etc/hadoop ${BREW_PREFIX}/Cellar/hadoop/2.7.3/libexec/etc/hadoop_default;

  # export hadoop envs
  if [ -d "${BREW_PREFIX}/Cellar/hadoop" ]; then
    export HADOOP_VERSION="$(brew list --versions hadoop | awk '{ print $2 }')";
    export HADOOP_HOME="${BREW_PREFIX}/Cellar/hadoop/${HADOOP_VERSION}";
    export HADOOP_CONF_DIR="${HADOOP_HOME}/libexec/etc/hadoop";
  fi
else
  echo "Aborting... Hadoop installation already exists";
fi

==> Downloading https://www.apache.org/dyn/closer.cgi?path=hadoop/common/hadoop-2.7.3/hadoop-2.7.3.tar.gz
Already downloaded: /Users/cvanzy/Library/Caches/Homebrew/downloads/fa29189d25e42f18e1b3c630e2e3081032991052ad49225c131534cad91d1cf7--hadoop-2.7.3.tar.gz
Warning: This keg was marked linked already, continuing anyway
Error: undefined method `undent' for #<String:0x0000000102342c10>
Please report this bug:
  https://docs.brew.sh/Troubleshooting
/Users/cvanzy/Library/Caches/Homebrew/Formula/hadoop.rb:38:in `caveats'
/usr/local/Homebrew/Library/Homebrew/caveats.rb:19:in `caveats'
/usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.3.7/lib/ruby/2.3.0/forwardable.rb:202:in `empty?'
/usr/local/Homebrew/Library/Homebrew/formula_installer.rb:618:in `caveats'
/usr/local/Homebrew/Library/Homebrew/formula_installer.rb:667:in `finish'
/usr/local/Homebrew/Library/Homebrew/cmd/install.rb:333:in `install_formula'
/usr/local/Homebrew/Library/Homebrew/cmd/install.rb:264:in `block in install'
/usr/local/Homebrew/Library/Homebrew/cmd/install.rb:262:in `each'
/usr/local/Homebrew/Library/Homebrew/cmd/install.rb:262:in `install'
/usr/local/Homebrew/Library/Homebrew/brew.rb:102:in `<main>'

It raises an error

By any chance have you already installed hadoop via brew previously?
If you run brew list do you see hadoop?
If you run hadoop version do you get a response?

I think I have installed version 3.1.2 before.
but when I decide to downgrade to 2.7, I use brew uninstall hadoop to remove the package.

For now, I configure that hadoop from scratch manually.

I got the same error unfortunately.