Why is composer init not working?

Question

Composer

Latest version. Any other commands work. For example, require will install everything in the same folder. What's wrong?

Exception trace

Exception trace:
 () at phar:///usr/bin/composer/vendor/symfony/console/Helper/QuestionHelper.php:138
 Symfony\Component\Console\Helper\QuestionHelper->doAsk() at phar:///usr/bin/composer/vendor/symfony/console/Helper/QuestionHelper.php:62
 Symfony\Component\Console\Helper\QuestionHelper->Symfony\Component\Console\Helper\{closure}() at phar:///usr/bin/composer/vendor/symfony/console/Helper/QuestionHelper.php:400
 Symfony\Component\Console\Helper\QuestionHelper->validateAttempts() at phar:///usr/bin/composer/vendor/symfony/console/Helper/QuestionHelper.php:65
 Symfony\Component\Console\Helper\QuestionHelper->ask() at phar:///usr/bin/composer/src/Composer/IO/ConsoleIO.php:266
 Composer\IO\ConsoleIO->askAndValidate() at phar:///usr/bin/composer/src/Composer/Command/InitCommand.php:231
 Composer\Command\InitCommand->interact() at phar:///usr/bin/composer/vendor/symfony/console/Command/Command.php:251
 Symfony\Component\Console\Command\Command->run() at phar:///usr/bin/composer/vendor/symfony/console/Application.php:861
 Symfony\Component\Console\Application->doRunCommand() at phar:///usr/bin/composer/vendor/symfony/console/Application.php:208
 Symfony\Component\Console\Application->doRun() at phar:///usr/bin/composer/src/Composer/Console/Application.php:245
 Composer\Console\Application->doRun() at phar:///usr/bin/composer/vendor/symfony/console/Application.php:127
 Symfony\Component\Console\Application->run() at phar:///usr/bin/composer/src/Composer/Console/Application.php:100
 Composer\Console\Application->run() at phar:///usr/bin/composer/bin/composer:54
 require() at /usr/bin/composer:24