fix(core): Recognize enums without type-attribute

Previously, enums without type-attribute weren't recognized by the
derive types function, leading to omitted enums in generated uischemas.

Closes #2177

packages/core/src/util/util.ts

@@ -77,7 +77,17 @@ export const deriveTypes = (jsonSchema: JsonSchema): string[] => {
   if (!isEmpty(jsonSchema.items)) {
     return ['array'];
   }
-
+  if (!isEmpty(jsonSchema.enum)) {
+    const types: Set<string> = new Set();
+    jsonSchema.enum.forEach((enumElement) => {
+      if (typeof enumElement === 'string') {
+        types.add('string');
+      } else {
+        deriveTypes(enumElement).forEach((type) => types.add(type));
+      }
+    });
+    return Array.from(types);
+  }
   if (!isEmpty(jsonSchema.allOf)) {
     const allOfType = find(
       jsonSchema.allOf,

packages/core/test/util/derivetype.test.ts

@@ -65,6 +65,23 @@ test('derive type w/o type - items array', (t) => {
   t.is(deriveTypes(schema)[0], 'array');
 });
 
+test('derive type w/o type - enum', (t) => {
+  const schema: JsonSchema = {
+    enum: ['foo', 'bar'],
+  };
+  t.is(deriveTypes(schema).length, 1);
+  t.is(deriveTypes(schema)[0], 'string');
+});
+
+test('derive type w/o type - enum with two types', (t) => {
+  const schema: JsonSchema = {
+    enum: ['foo', 'bar', { properties: { foo: { type: 'string' } } }],
+  };
+  t.is(deriveTypes(schema).length, 2);
+  t.is(deriveTypes(schema)[0], 'string');
+  t.is(deriveTypes(schema)[1], 'object');
+});
+
 test('derive type with type - union', (t) => {
   const schema: JsonSchema = {
     type: ['string', 'number'],