Some selections result in errors about code-struct

[vicchig]

This is occurring due the editor always searching for the next empty token upon insertion of a code construct. (See ast.ts below)

However, not all constructs have an empty token. For example boolean literals True and False, and the keyword Else, do not have an empty token to return. Line 2423 will return NULL and line 2424 then attempts to call getSelection() on NULL.

If possible, it would probably be good to add a new token type that is just a placeholder for where to put the cursor if there is nowhere else it can go. Currently it looks like a lot of the navigation relies on having this "empty" token somewhere within an expression or statement, but not all of them have these. Not sure, if there is a better fix.

[MajeedKazemi]

fixed with #110