fix: some analysis stage problems

tests/programs/pos_function_external_call.fzs

@@ -0,0 +1,12 @@
+fn doSomeWork()
+{
+  printline("Some work");
+}
+
+fn sum(int a, int b) int
+{
+  return a + b;
+}
+
+int result = sum(5, 6);
+printline(result);