fix: prevent infinite loop while process circular nested type

Author: async3619

package.json

@@ -1,7 +1,7 @@
 {
     "name": "ts-bookshelf",
     "description": "generate markdown-based documentation from typescript types",
-    "version": "1.0.0-next.2",
+    "version": "1.0.0-next.3",
     "license": "MIT",
     "source": "src/index.ts",
     "main": "dist/common.js",

src/generators/class.ts

@@ -42,6 +42,10 @@ export function generateForClass(classType: ClassType, options?: DocumentOptions
     if (combineNestedFields) {
         const customClasses = fields.filter(f => f.isCustom);
         for (const customClass of customClasses) {
+            if (customClass.type === classType) {
+                continue;
+            }
+
             contents.push(
                 ...generateForClass(customClass.type, {
                     ...options,