Post checkout hook does not honor the inputs that git provides

[ayush-sd]

Troubleshoot

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Context
Please describe your issue and provide some context:
Running husky on mac in zsh shell

I created post-checkout hook which receives two inputs from git -

the ref of the previous HEAD, the ref of the new HEAD

I use this to check for diff in package.json and notify if package.json has changed when you checkout

This hook runs fine if I add it in .git/hooks folder but when I try to add it to husky, husky runs the hook without providing the two inputs HEADs that git does and the hook fails.

Here is the hook:

# Checks if package.json has been changed when you checkout a branch
# If changed, then it will print a warning to nudge the user to reinstall packages.

# Define colors
RED='\033[0;31m'
YELLOW='\033[0;33m'

PACKAGE_ICON='📦'
ARROW_ICON='➜'

PREV_COMMIT=$1
POST_COMMIT=$2

echo $PACKAGE_ICON
echo $PREV_COMMIT # prints empty line if run via husky
echo $POST_COMMIT # prints empty line if run via husky

# Compare package.json between commits
DIFF=$(git diff --name-only "$PREV_COMMIT".."$POST_COMMIT" | grep "package.json")

# If package.json has changed, display warning
if [[ -n "$DIFF" ]]; then
    echo "${YELLOW}===============================\n"
    echo "${YELLOW}${PACKAGE_ICON} package.json changes detected ${PACKAGE_ICON}${NC}\n"
    echo "${YELLOW}==============================="

    git diff --unified=0 "$PREV_COMMIT".."$POST_COMMIT" package.json
fi

Screenshot of the error

[ayush-sd]

I get the proper HEAD refs if I run the same hook without using husky by putting it inside .git/hooks