Life is complicated. PHP can be, too.
Psalm is designed to understand that complexity, allowing it to quickly find common programmer errors like null references and misspelled variable names.
You should use Psalm if want to
Psalm has a number of features that help you improve your codebase, including a fixer called Psalter that updates your code directly by leveraging Psalm’s analysis engine.
Interested in how Psalm came to be? Read this explainer.