Fix: properly escape closing identifier delimiters

[georgesittas]

Only related SO thread I found is this one, but I played using T-SQL and concluded that [ after the opening bracket doesn't need to be escaped, but ] does because it needs to be disambiguated from the closing delimiter:

1> SELECT 1 AS [[x]]], 1 AS "[y]"
2> GO
[x]         [y]        
----------- -----------
          1           1