Revamp analyser to handle undefined channels without panicking

[nickng]

Panics should not be used for handling undefined channel variables. The following should be tried before panicking:

• Use pointer analysis to find possible source of channel
• Dummy out a new channel variable on the fly if the channel is used in multiple places
• Flag as an error but continue analysis
• When initialising new struct, use zero value to fully initialise memory (not just the field being accessed)