interp/type.go can return a nil value (and no error, either) in nodetype2, which causes a panic

[theclapp]

The following program sample.go triggers an unexpected result

n/a

Expected result

Error

Got

panic

Yaegi Version

381e045

Additional Notes

I'm having a hard time reproducing this at the moment, but the t == nil line in the below snippet from interp/type.go allows returning a nil value from nodetype2, which lots of places use without checking if it's nil (including right inside nodetype2), which causes a panic:

yaegi/interp/type.go

Lines 1119 to 1127 in 381e045

	switch {
	case t == nil:
	case t.name != "" && t.path != "":
	t.str = t.path + "." + t.name
	case t.cat == nilT:
	t.str = "nil"
	}
	return t, err

I suspect that me hitting this case was a result of using Yaegi incorrectly (possibly from using ImportUsed but not actually importing those packages in the Eval'ed code), which I'm not doing any more, which is why I'm not seeing it, but I feel like the t == nil case should clearly at least return an error.