add error messages

tests/13_err-no-main.test

@@ -1,3 +1,3 @@
-void test () {
+void test () { # Error on line 0 col -1: No main function.
     bool a = false;
 }

tests/14_err-too-much-args.test

@@ -3,5 +3,5 @@ int foo (int a) {
 }
 
 void main () {
-    foo(13, 12);
+    foo(13, 12); # Error on line 6 col 8: Expected 1 arguments but given 2.
 }

tests/15_err-args-missing.test

@@ -3,5 +3,5 @@ int foo (int a, int b) {
 }
 
 void main () {
-    foo(42);
+    foo(42); # Error on line 6 col 8: Expected 2 arguments but given 1.
 }