tests: Don't call visit_end_struct() after visit_start_struct() fails

When visit_start_struct() fails, visit_end_struct() must not be
called.  Three out of four visit_type_TestStruct() call it anyway.  As
far as I can tell, visit_start_struct() doesn't actually fail there.
Fix them anyway.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

tests/test-qmp-input-strict.c

@@ -72,14 +72,22 @@ typedef struct TestStruct
 static void visit_type_TestStruct(Visitor *v, TestStruct **obj,
                                   const char *name, Error **errp)
 {
+    Error *err = NULL;
+
     visit_start_struct(v, (void **)obj, "TestStruct", name, sizeof(TestStruct),
-                       errp);
+                       &err);
+    if (err) {
+        goto out;
+    }
+
+    visit_type_int(v, &(*obj)->integer, "integer", &err);
+    visit_type_bool(v, &(*obj)->boolean, "boolean", &err);
+    visit_type_str(v, &(*obj)->string, "string", &err);
 
-    visit_type_int(v, &(*obj)->integer, "integer", errp);
-    visit_type_bool(v, &(*obj)->boolean, "boolean", errp);
-    visit_type_str(v, &(*obj)->string, "string", errp);
+    visit_end_struct(v, &err);
 
-    visit_end_struct(v, errp);
+out:
+    error_propagate(errp, err);
 }
 
 static void test_validate_struct(TestInputVisitorData *data,

tests/test-qmp-output-visitor.c

@@ -176,14 +176,22 @@ typedef struct TestStruct
 static void visit_type_TestStruct(Visitor *v, TestStruct **obj,
                                   const char *name, Error **errp)
 {
+    Error *err = NULL;
+
     visit_start_struct(v, (void **)obj, "TestStruct", name, sizeof(TestStruct),
-                       errp);
+                       &err);
+    if (err) {
+        goto out;
+    }
+
+    visit_type_int(v, &(*obj)->integer, "integer", &err);
+    visit_type_bool(v, &(*obj)->boolean, "boolean", &err);
+    visit_type_str(v, &(*obj)->string, "string", &err);
 
-    visit_type_int(v, &(*obj)->integer, "integer", errp);
-    visit_type_bool(v, &(*obj)->boolean, "boolean", errp);
-    visit_type_str(v, &(*obj)->string, "string", errp);
+    visit_end_struct(v, &err);
 
-    visit_end_struct(v, errp);
+out:
+    error_propagate(errp, err);
 }
 
 static void test_visitor_out_struct(TestOutputVisitorData *data,

tests/test-visitor-serialization.c

@@ -195,13 +195,21 @@ typedef struct TestStruct
 static void visit_type_TestStruct(Visitor *v, TestStruct **obj,
                                   const char *name, Error **errp)
 {
-    visit_start_struct(v, (void **)obj, NULL, name, sizeof(TestStruct), errp);
+    Error *err= NULL;
 
-    visit_type_int(v, &(*obj)->integer, "integer", errp);
-    visit_type_bool(v, &(*obj)->boolean, "boolean", errp);
-    visit_type_str(v, &(*obj)->string, "string", errp);
+    visit_start_struct(v, (void **)obj, NULL, name, sizeof(TestStruct), &err);
+    if (err) {
+        goto out;
+    }
+
+    visit_type_int(v, &(*obj)->integer, "integer", &err);
+    visit_type_bool(v, &(*obj)->boolean, "boolean", &err);
+    visit_type_str(v, &(*obj)->string, "string", &err);
+
+    visit_end_struct(v, &err);
 
-    visit_end_struct(v, errp);
+out:
+    error_propagate(errp, err);
 }
 
 static TestStruct *struct_create(void)