NPE when instantiating a system with unbound prototype

[jjhugues]

Summary
In issue saeaadl/aadlv2.2#19, the following example is reported

package issue19
public
	system s
		-- ...
	end s;

	system implementation s.i
		prototypes
			X: bus;
			-- ...
		subcomponents
			b: bus X;
			-- ...
	end s.i;

	system T

	end T;

	system implementation T.i
	subcomponents
		sub1: system s.i; -- no prototype binding
		-- ...
	end T.i;
	
end issue19;

Expected behavior

OSATE should either instantiate the model or reject it. From the original issue, it should be rejected since the prototype is not bound. The OP hints as some specific behavior OSATE implements

Actual behavior

OSATE reports a NPE

Steps To Reproduce

• Instantiate T.i

[lwrage]

Instantiation could be done with a warning on the subcomponent that an unbound prototype was used.

s.i from the example can be treated during instantiation as

system implementation s.i
	subcomponents
		b: bus;
end s.i;

Whenever an prototype has a classifier that classifier can be instantiated.

[lwrage]

No longer reproducible in 2.15.0 nightly.