fix: add missing dependency typedoc

Fixes #5

src/schema.ts

@@ -108,6 +108,10 @@ export class Converter {
 export function getValidatableTypesFromReflection(projectReflection: ProjectReflection): string[] {
   const validatableTypes: string[] = [];
 
+  if (typeof projectReflection.children === 'undefined') {
+    throw new Error('Project reflection doesn\'t contain any modules.');
+  }
+
   // iterate over modules
   projectReflection.children.forEach((module) => {
     if (Array.isArray(module.children) && module.children.length > 0) {