Fix some bugs in Chapter 05

There are 2 big bugs:

About line 88: https://github.com/DiscoverMeteor/Microscope/commit/chapter5-1#diff-86268a1481d515783ec8f86fe20f0fd6R9

About line 165: See: https://github.com/DiscoverMeteor/Microscope/commit/chapter5-2#diff-504fd89f344be1e9c4b583f3ebd7428aR11