Protecting against seg faults
Protecting against seg faults

Checking in a few checks/assertions to head off a seg fault that can
occur when trying to generate a field of a nil instance variable.
This happened for me when declaring a class with members along the
lines of:

      class D {
        var x: C;
        var y: [C.foo] real;
      }

If x is nil, I got a seg fault when the compiler was generating
the class constructor.  Now it gives an internal error.



git-svn-id: 88467cb1fb04b8a755be7e1ee1026be4190196ef@14588 3a8e244f-b0f2-452b-bcba-4c88e055c3ca

chizarlicious/chapel,sungeunchoi/chapel,sungeunchoi/chapel,chizarlicious/chapel,hildeth/chapel,CoryMcCartan/chapel,CoryMcCartan/chapel,sungeunchoi/chapel,chizarlicious/chapel,CoryMcCartan/chapel,hildeth/chapel,sungeunchoi/chapel,hildeth/chapel,CoryMcCartan/chapel,hildeth/chapel,chizarlicious/chapel,hildeth/chapel,hildeth/chapel,chizarlicious/chapel,sungeunchoi/chapel,chizarlicious/chapel,chizarlicious/chapel,sungeunchoi/chapel,sungeunchoi/chapel,CoryMcCartan/chapel,CoryMcCartan/chapel,hildeth/chapel,sungeunchoi/chapel,CoryMcCartan/chapel