Get a IndexEntry by index.
Note that the returned IndexEntry is _only_ valid as long as:
1) The associated index has been closed 2) The entry has not been removed (see remove ) 3) The index has not been refreshed (see read)
Changes to the IndexEntry will be reflected in the index once written back to disk using write.
| this |
a IndexEntries. |
| idx |
the index of the entry. |
|
a IndexEntry or null if out of bounds. |