fix some bugs

ui-tests/functions/missing_args.nil

@@ -0,0 +1,5 @@
+function main() = (
+    x();
+);
+
+function x(a: Int) = ;

ui-tests/functions/missing_args.stderr

@@ -0,0 +1,4 @@
+error: missing argument of type Int
+ --> $DIR/missing_args.nil:2
+2 |     x();
+         ^

ui-tests/type/generics/codegen.nil

@@ -0,0 +1,11 @@
+//@check-pass
+type A[T] = struct { a: T };
+type B[T, U, V] = struct {
+  b: T,
+  d: V,
+};
+type C = ();
+
+function main() = ;
+
+function test(a: A[I32], b: B[I32, Int, I32], c: C) = ;