Segmentation fault: StkInstrument

[spencersalazar]

The following code fails with a segmentation fault:

StkInstrument u => blackhole;
1::samp => now;
u =< blackhole;
null @=> u;

likely because StkInstrument is an abstract base class.

[briansorahan]

This issue and #1 seem to be two symptoms of the same cause, which is that chuck does a bad job of handling compile-time failures when trying to instantiate stk abc's (Instrmnt in this case, and Filter for #1).