Crash: Trying to get property 'message' of non-object

[sbrl]

When I try to use this package, I get this error:

/home/sbrl/.atom/packages/linter/lib/linter-registry.js:155 [Linter] Error running PHPMD Error: PHP Notice:  Trying to get property 'message' of non-object in /home/sbrl/.config/composer/vendor/phpmd/phpmd/src/main/php/PHPMD/RuleSetFactory.php on line 236
PHP Stack trace:
PHP   1. {main}() /home/sbrl/.config/composer/vendor/phpmd/phpmd/src/bin/phpmd:0
PHP   2. PHPMD\TextUI\Command::main() /home/sbrl/.config/composer/vendor/phpmd/phpmd/src/bin/phpmd:122
PHP   3. PHPMD\TextUI\Command->run() /home/sbrl/.config/composer/vendor/phpmd/phpmd/src/main/php/PHPMD/TextUI/Command.php:173
PHP   4. PHPMD\PHPMD->processFiles() /home/sbrl/.config/composer/vendor/phpmd/phpmd/src/main/php/PHPMD/TextUI/Command.php:129
PHP   5. PHPMD\RuleSetFactory->createRuleSets() /home/sbrl/.config/composer/vendor/phpmd/phpmd/src/main/php/PHPMD/PHPMD.php:217
PHP   6. PHPMD\RuleSetFactory->createSingleRuleSet() /home/sbrl/.config/composer/vendor/phpmd/phpmd/src/main/php/PHPMD/RuleSetFactory.php:125
PHP   7. PHPMD\RuleSetFactory->parseRuleSetNode() /home/sbrl/.config/composer/vendor/phpmd/phpmd/src/main/php/PHPMD/RuleSetFactory.php:141
    at ChildProcess.<anonymous> (/home/sbrl/.atom/packages/linter-lua/node_modules/sb-exec/lib/index.js:56:20)
    at emitTwo (events.js:126:13)
    at ChildProcess.emit (events.js:214:7)
    at maybeClose (internal/child_process.js:925:16)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:209:5)

I installed phpmd with this: composer global require phpmd/phpmd

...and then put this in the phpmd path settings box: /home/sbrl/.config/composer/vendor/phpmd/phpmd/src/bin/phpmd.