Any input of an expression with empty string (see the attachments) does invalid syntax highlighting.
The problem in the first place is that the code you entered is not correct.
How would you want it to be highlighted?
Isn't it OK? Both examples run fine. The first highlights OK for me but not the second.
The new expression 'println("" + "hello")' must not highlight fine anywhere.
The empty double quoted example was fixed sometime, but for empty single quoted strings the highlighting is still incorrect.
Submitted a pull request for this.
pull request merged