Getting an "Unspecified AssertionError" on test:

candidate: {
	skills:
	[{
			name: 'Python',
			experience: 4,
			preference: 'neutral'
		}, {
			name: 'Java',
			experience: 4,
			preference: 'neutral'
		}, {
			name: 'Haskell',
			experience: 7,
			preference: 'avoid'
		}
	]
}
job: {
	skills:
	[{
			name: 'Python',
			idealYears: 3,
			substitutions: [ { name: 'Python' } ]
		}
	]
}

Running fine locally.

Why is this false?
+------+
| |
X-----+------+
|
X
The only valid path is down at the first +.

If I go up, then right then down then left, I need to go thorugh the same + again, which is invalid (same if I go drom second X)