tests: fix option_print_errors_test.v (#9616)

cmd/tools/vtest-self.v

@@ -209,7 +209,6 @@ fn main() {
 	mut tsession := testing.new_test_session(cmd_prefix)
 	tsession.files << all_test_files
 	tsession.skip_files << skip_test_files
-	tsession.skip_files << 'vlib/v/tests/option_print_errors_test.v'
 	mut werror := false
 	mut sanitize_memory := false
 	mut sanitize_address := false

vlib/v/tests/option_print_errors_test.v

@@ -1,10 +1,10 @@
 fn test_error_can_be_converted_to_string() {
-	assert 'Option{ error: "an error" }' == error('an error').str()
+	assert 'an error' == error('an error').str()
 }
 
 fn test_error_can_be_assigned_to_a_variable() {
 	f := error('an error')
-	assert 'Option{ error: "an error" }' == f.str()
+	assert 'an error' == f.msg
 }
 
 fn test_error_can_be_printed() {
@@ -16,5 +16,5 @@ fn test_error_can_be_printed() {
 fn test_error_can_be_interpolated_in_a_string() {
 	f := error('an error')
 	s := 'hi $f'
-	assert s == 'hi Option{ error: "an error" }'
+	assert s == 'hi an error'
 }