feat: add error handling for duplicate or not exists

packages/file-graph/fileNode.js

@@ -1,5 +1,6 @@
 import path from 'path'
 import File from './file.js'
+import { DuplicateItemError, ParentNotExistsError } from './errors.js'
 
 export default class FileNode extends File {
   constructor(file) {
@@ -10,7 +11,11 @@ export default class FileNode extends File {
   addChild(fileInput) {
     const file = new File(fileInput)
     if (file.path === this.path) {
-      throw new Error('File already exists in the tree')
+      throw new DuplicateItemError('File already exists in the tree')
+    }
+
+    if (this.children.some((child) => child.path === file.path)) {
+      throw new DuplicateItemError('File already exists in the tree')
     }
 
     const parentPath = path.dirname(file.path)
@@ -23,19 +28,17 @@ export default class FileNode extends File {
       if (childNode) {
         childNode.addChild(file)
       } else {
-        console.log(fileInput, this)
-        throw new Error('Parent path not found in the tree')
+        throw new ParentNotExistsError('Parent path not found in the tree')
       }
     }
   }
 
   toString() {
     const indent = '    '.repeat(this.path.split('/').length - 1)
+    const suffix = this.isDirectory() ? '/' : ''
     const childrenString = this.children
       .map((child) => child.toString())
       .join('')
-    return `${indent}${this.name}${
-      this.isDirectory() ? '/' : ''
-    }\n${childrenString}`
+    return `${indent}${this.name}${suffix}\n${childrenString}`
   }
 }