Fix enum being empty (#563)

Fall back to its default type of no enums given (TypeScript lacks an “empty enum” type)

Author: drwpow

.node-version

@@ -0,0 +1 @@
+15

src/utils.ts

@@ -31,7 +31,7 @@ export function nodeType(obj: any): SchemaObjectType | undefined {
   }
 
   // enum
-  if (Array.isArray(obj.enum)) {
+  if (Array.isArray(obj.enum) && obj.enum.length) {
     return "enum";
   }
 

tests/schema.test.ts

@@ -211,6 +211,13 @@ describe("SchemaObject", () => {
 "string"?: (('Totoro') | (2) | (false)) | null;
 
 }`);
+
+      expect(transform({ properties: { string: { type: "string", enum: [] } }, type: "object" })).toBe(
+        `{
+"string"?: string;
+
+}`
+      );
     });
 
     it("$ref", () => {