By the rules defined at Optional Braces you cannot seem to remove the braces in your case:
An indent is inserted at a line break, if
1. An indentation region can start at the current position in the source, and
2. the first token on the next line has an indentation width strictly greater than the current indentation width
An indentation region can start
* after the leading parameters of an extension, or
* after a with in a given instance, or
* after a ": at end of line" token (see below)
* after one of the following tokens:
= => ?=> <- catch do else finally for if match return then throw try while yield