IndexError(int invalidValue, indexable, [ String name, String message, int length ])

Creates a new IndexError stating that invalidValue is not a valid index into indexable.

The length is the length of indexable at the time of the error. If length is omitted, it defaults to indexable.length.

The message is used as part of the string representation of the error.

Source 

IndexError(int invalidValue, indexable,
           [String name, String message, int length])
    : this.indexable = indexable,
      this.length = (length != null) ? length : indexable.length,
      super.value(invalidValue, name,
                  (message != null) ? message : "Index out of range");