Java 6+ / Oracle implementation (Cracked by feersumCracked by feersum)
Code (226 bytes)
There are 5 new line characters and 2 spaces. No other invisible/non-printable character presents.
""" ((((((()))))))++,........
00000000000001122225677788
;;;DEIPPSSS[\\\\\\\]aaaaaaaaaaaabccccccccddeeeeeeeeeeeef
gggghiiiiiiiiiiiijllllmmmmnnnnnnnnnoooooopppppprrrrrrrr
sssssstttttttttttttttttttuuuuuuuuuuuuuvvxxyyyz
{{{{}}}}
Output
91 Unmatched closing ')'
The program has been tested to compile and run successfully on ideone, so please submit an answer with runnable demo there.
feersum's solution is far from my intended solution, so I will not reveal my intended solution since I'm going to modify it for a new challenge.