class Prism::Pattern::CompilationError

is using syntax that we don’t yet support.
Raised when the query given to a pattern is either invalid Ruby syntax or

def initialize(repr)

that caused the error.
Create a new CompilationError with the given representation of the node 
def initialize(repr)
  super(<<~ERROR)
    prism was unable to compile the pattern you provided into a usable
    expression. It failed on to understand the node represented by:
    #{repr}
    Note that not all syntax supported by Ruby's pattern matching syntax
    is also supported by prism's patterns. If you're using some syntax
    that you believe should be supported, please open an issue on
    GitHub at https://github.com/ruby/prism/issues/new.
  ERROR
end