test: update error expectations for variable resolution tests

Author: ryan-gang

test_programs/r4/1.lox

@@ -2,5 +2,5 @@
 expected_error_type: none
 ---
 var a = "value";
-var a = a;
+var a = a; // global scope, so this is allowed
 print a; // expect: value

test_programs/r5/1.lox

@@ -1,3 +1,4 @@
 ---
-expected_error_type: none
+expected_error_type: compile
 ---
+return "foo";

test_programs/r6/2.lox

@@ -1,6 +1,6 @@
 ---
-expected_error_type: compile
+expected_error_type: runtime
 ---
-print a; // expect: compile error
+print a; // expect: runtime error
 var a = "value";
 print a; // expect: value