tests/qapi-schema: Drop superfluous error_is_set()

visit_type_TestStruct() does nothing when called with an error set.
Callers shouldn't do that, and no caller does.  Drop the superfluous
test.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMichael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

tests/test-qmp-input-visitor.c

@@ -196,21 +196,20 @@ static void visit_type_TestStruct(Visitor *v, TestStruct **obj,
                                   const char *name, Error **errp)
 {
     Error *err = NULL;
-    if (!error_is_set(errp)) {
-        visit_start_struct(v, (void **)obj, "TestStruct", name, sizeof(TestStruct),
-                           &err);
-        if (!err) {
-            visit_type_int(v, &(*obj)->integer, "integer", &err);
-            visit_type_bool(v, &(*obj)->boolean, "boolean", &err);
-            visit_type_str(v, &(*obj)->string, "string", &err);
-
-            /* Always call end_struct if start_struct succeeded.  */
-            error_propagate(errp, err);
-            err = NULL;
-            visit_end_struct(v, &err);
-        }
+
+    visit_start_struct(v, (void **)obj, "TestStruct", name, sizeof(TestStruct),
+                       &err);
+    if (!err) {
+        visit_type_int(v, &(*obj)->integer, "integer", &err);
+        visit_type_bool(v, &(*obj)->boolean, "boolean", &err);
+        visit_type_str(v, &(*obj)->string, "string", &err);
+
+        /* Always call end_struct if start_struct succeeded.  */
         error_propagate(errp, err);
+        err = NULL;
+        visit_end_struct(v, &err);
     }
+    error_propagate(errp, err);
 }
 
 static void test_visitor_in_struct(TestInputVisitorData *data,