Unclosed If Expressions

[lucifer1004]

I believe this is a caveat of the WAIIG book, not of a specific implementation.

Currently, the following code (an unclosed if expression)

if (true) { puts(2)

is parsed and evaluated as a valid expression.

[lucifer1004]

This can be handled by adding an extra argument to parse_block_statements to indicate whether the block must be closed with an RBRACE.