add example sources failing syntax and typing

examples/failing/syntax/addition.lila

@@ -0,0 +1,3 @@
+fn add(a: int, b: int) int {
+	a +
+}

examples/failing/type/addition.lila

@@ -0,0 +1,16 @@
+fn add(a: int, b: float) int {
+	a + b
+}
+
+fn add2(a: int, b: int) float {
+	a + b
+}
+
+fn add3(a: int, b: float) int {
+	return b;
+	a
+}
+
+fn add4(a: int, b: int) {
+	a
+}