Fixed NPE on quick assist proposals

In the former implementation, the implicit conversion `Predef.refArrayOps`
could be applied on a `null` value, because `null` was returned if
`corrections.isEmpty` was true, leading to a NPE.

Fix #1002014
Merge pull request #618 from dotta/issue/npe-on-quickassist-1002014

Fixed NPE on quick assist proposals
Using the enclosed type to fix completion and imports for inner classes.

Make sure that the enclosing object is passed to the indexer also for modules.

Fix #1002002
Merge pull request #607 from tbje/fix-inner-type-completion-#1002002

Using the enclosed type to fix completion and imports for inner classes.