Fix compiler crash on missing let body

test/aeso_compiler_tests.erl

@@ -208,7 +208,11 @@ failing_contracts() ->
         <<"Repeated argument y to function repeated_arg (at line 44, column 12).">>,
         <<"No record type with fields y, z (at line 14, column 22)">>,
         <<"The field z is missing when constructing an element of type r2 (at line 15, column 24)">>,
-        <<"Record type r2 does not have field y (at line 15, column 22)">>]}
+        <<"Record type r2 does not have field y (at line 15, column 22)">>,
+        <<"Let binding at line 47, column 5 must be followed by an expression">>,
+        <<"Let binding at line 50, column 5 must be followed by an expression">>,
+        <<"Let binding at line 54, column 5 must be followed by an expression">>,
+        <<"Let binding at line 58, column 5 must be followed by an expression">>]}
     , {"init_type_error",
        [<<"Cannot unify string\n"
           "         and map(int, int)\n"

test/contracts/type_errors.aes

@@ -42,3 +42,18 @@ contract Test =
     set_x(set_x(x, r), x)
 
   function repeated_arg(x : int, y, x : string, y : bool) : string = x
+
+  function missing1() =
+    let x = 0
+
+  function missing_fun1() =
+    let f(x) = x
+
+  function missing2() =
+    let x = 0
+    let y = 0
+
+  function missing_fun2() =
+    let f() = 0
+    let g() = f()
+