class ExecJS::ExternalRuntime

def exec_runtime_error(output)
  error = RuntimeError.new(output)
  lines = output.split("\n")
  lineno = lines[0][/:(\d+)$/, 1] if lines[0]
  lineno ||= 1
  error.set_backtrace(["(execjs):#{lineno}"] + caller)
  error
end