diff --git a/tests/validate_animations.test.js b/tests/validate_animations.test.js
index 1a3c4ea..8d3f400 100644
--- a/tests/validate_animations.test.js
+++ b/tests/validate_animations.test.js
@@ -12,6 +12,24 @@ const ajv = new Ajv({
 });
 const validate = ajv.compile(schema);
 
+expect.extend({
+    toBeValid(data) {
+
+        if ( validate(data) )
+        {
+            return {
+                message: () => "data NOT be valid",
+                pass: true
+            };
+        }
+
+        return {
+            message: () => "Invalid data: " + JSON.stringify(validate.errors, null, 4),
+            pass: false
+        };
+    }
+});
+
 describe('run schema validation', () => {
     describe('example animations', () => {
         const exampleFiles = fs.readdirSync(EXAMPLES_DIR).map(file => EXAMPLES_DIR + file);
@@ -19,9 +37,7 @@ describe('run schema validation', () => {
         exampleFiles.forEach((file) => {
             test(file, () => {
                 const animation = fs.readFileSync(file, 'utf8');
-                const valid = validate(JSON.parse(animation));
-    
-                expect(valid).toBe(true);
+                expect(JSON.parse(animation)).toBeValid();
             });
         });
     });
@@ -33,7 +49,7 @@ describe('run schema validation', () => {
             test(file, () => {
                 const animation = fs.readFileSync(file, 'utf8');
                 const valid = validate(JSON.parse(animation));
-    
+
                 expect(valid).toBe(true);
             });
         });
@@ -46,7 +62,7 @@ describe('run schema validation', () => {
             test(file, () => {
                 const animation = fs.readFileSync(file, 'utf8');
                 const valid = validate(JSON.parse(animation));
-    
+
                 expect(valid).toBe(false);
             });
         });
diff --git a/tools/lottie_markdown.py b/tools/lottie_markdown.py
index 5dd8d76..3ad20c5 100644
--- a/tools/lottie_markdown.py
+++ b/tools/lottie_markdown.py
@@ -512,12 +512,13 @@ def handleMatch(self, match, data):
         schema_obj = self.schema_data.from_path(match.group("path"))
 
         for row in schema_obj.concrete:
-            tr = etree.SubElement(tbody, "tr")
-            prop_schema = row.properties[attribute]
-            etree.SubElement(etree.SubElement(tr, "td"), "code").text = repr(prop_schema.const)
+            prop_schema = row.properties.get(attribute)
+            if prop_schema:
+                tr = etree.SubElement(tbody, "tr")
+                etree.SubElement(etree.SubElement(tr, "td"), "code").text = repr(prop_schema.const)
 
-            td = etree.SubElement(tr, "td")
-            row.link.to_element(td, self.md)
+                td = etree.SubElement(tr, "td")
+                row.link.to_element(td, self.md)
 
         return table, match.start(0), match.end(0)
 
diff --git a/tools/schema-merge.py b/tools/schema-merge.py
index bd56f09..326fa9a 100755
--- a/tools/schema-merge.py
+++ b/tools/schema-merge.py
@@ -41,9 +41,9 @@ def add_vals_to_unknown_object(
     types = []
 
     for ele in objects.concrete:
-        type = ele.properties['ty'].const
-        if type is not None:
-            types.append(type)
+        type = ele.properties.get('ty', None)
+        if type is not None and type.const is not None:
+            types.append(type.const)
 
     unknown_type_dict["properties"]["ty"]["not"]["enum"] = types
 
diff --git a/tools/schema_tools/type_info.py b/tools/schema_tools/type_info.py
index f2f3b7e..ce1a209 100644
--- a/tools/schema_tools/type_info.py
+++ b/tools/schema_tools/type_info.py
@@ -27,6 +27,16 @@ def load(path):
             schema_data = Schema(json.load(file))
         return TypeSystem(schema_data)
 
+    def resolve_type(self, schema: Schema):
+        if "oneOf" in schema:
+            local_type = schema.get("type", None)
+            if local_type is not None:
+                return local_type
+            return [self.resolve_type(choice) for choice in schema / "oneOf"]
+        if "$ref" in schema:
+            return self.types[schema["$ref"]]
+        return schema.get("type", None)
+
 
 class Type:
     def __init__(self, type_system: TypeSystem, schema: Schema):
@@ -50,20 +60,10 @@ def __init__(self, type_system: TypeSystem, schema: Schema):
         super().__init__(type_system, schema)
         self.const = schema.get("const", None)
 
-    def resolve_type(self, schema: Schema):
-        if "oneOf" in schema:
-            local_type = schema.get("type", None)
-            if local_type is not None:
-                return local_type
-            return [self.resolve_type(choice) for choice in schema / "oneOf"]
-        if "$ref" in schema:
-            return self.type_system.types[schema["$ref"]]
-        return schema.get("type", None)
-
     def resolve(self):
-        self.type = self.resolve_type(self.schema)
+        self.type = self.type_system.resolve_type(self.schema)
         if "items" in self.schema:
-            self.item_type = self.resolve_type(self.schema / "items")
+            self.item_type = self.type_system.resolve_type(self.schema / "items")
         else:
             self.item_type = ""
 
@@ -89,6 +89,12 @@ def __init__(self, type_system: TypeSystem, schema: Schema):
     def get_properties(self, schema: Schema):
         if "properties" in schema:
             for name, value in (schema / "properties").items():
+                if (
+                    isinstance(value.schema, dict) and
+                    len(value.schema) == 1 and
+                    list(value.schema.keys())[0] == "not"
+                ):
+                    continue
                 self.properties[name] = Property(self.type_system, value)
 
     def resolve(self):