src/Index/IndexManager.php
public function getIndex($name = null)
    {
        if (null === $name) {
            return $this->defaultIndex;
        }

        if (!isset($this->indexes[$name])) {
            throw new \InvalidArgumentException(sprintf('The index "%s" does not exist', $name));
        }

        return $this->indexes[$name];
    }
public function getIndex($name = null)
    {
        if (null === $name) {
            return $this->defaultIndex;
        }

        if (!isset($this->indexes[$name])) {
            throw new \InvalidArgumentException(sprintf('The index "%s" does not exist', $name));
        }

        return $this->indexes[$name];
    }
Gets an index by its name.

@param string $name Index to return, or the default index if null

@return Index

@throws \InvalidArgumentException if no index exists for the given name