Hovers and completions break when the cursor is above whitespace

[thinker227]

Hovers and completions in the language server break when the cursor position is in what is technically whitespace. This is especially annoying when the cursor position is one past the end of a node (foo|) which makes completions completely unusable.

This also causes misplaced symbol completions because the node under the cursor might technically be in the surrounding block.

{
    print(x);
    |
    print(y);
}

Introducing whitespace-aware tokens (#29) would likely fix this issue because the span of nodes would leech off any associated whitespace.