UnboundLocalError of line_shape variable while using ExtraTreeClassifier

[karanranawat]

ISSUE
Following error trace was encountered while running ti._predict_forest function for ExtraTreeClassifier model. This works perfectly for RandomForestClassifier.

POTENTIAL CAUSE
Following code block initializes line_shape variable.

treeinterpreter/treeinterpreter/treeinterpreter.py

Lines 56 to 66 in a52a6d7

	# reshape if squeezed into a single float
	if len(values.shape) == 0:
	values = np.array([values])
	if isinstance(model, DecisionTreeRegressor):
	biases = np.full(X.shape[0], values[paths[0][0]])
	line_shape = X.shape[1]
	elif isinstance(model, DecisionTreeClassifier):
	# scikit stores category counts, we turn them into probabilities
	normalizer = values.sum(axis=1)[:, np.newaxis]
	normalizer[normalizer == 0.0] = 1.0
	values /= normalizer

I see there are blocks specific to DecisionTreeRegressor and DecisionTreeClassifer while initializing line_shape variable.

Do we need to add something specific to Extra Tree Classifier?