add some error cases

Author: mattjohnsonpint

tests/compiler/call-rest.json

@@ -1,4 +1,7 @@
 {
   "asc_flags": [
+  ],
+  "stderr": [
+    "TS2322: Type '~lib/string/String' is not assignable to type 'i32'."
   ]
 }

tests/compiler/call-rest.ts

@@ -52,3 +52,7 @@ assert(count<i32>(1, 2, 3) == 3);
 
 // inferred generic test
 assert(count('a','b','c') == 3);
+
+// error cases
+count<i32>("a", "b"); // expect a type mismatch error on each argument
+count(1, "a"); // expect a type mismatch error on the second argument