Add missing type check of init function

test/contracts/init_type_error.aes

@@ -0,0 +1,8 @@
+
+contract InitTypeError =
+
+  type state = map(int, int)
+
+  // Check that the compiler catches ill-typed init function
+  function init() = "not the right type!"
+

test/contracts/missing_state_type.aes

@@ -0,0 +1,6 @@
+
+contract MissingStateType =
+
+  // Check that we get a type error also for implicit state
+  function init() = "should be ()"
+