title: TS2451: Cannot redeclare block-scoped variable 'custom'
body: <p>I'm using typescript in a web project. I use <code>awesome-typescript-loader</code> as a <code>webpack</code> loader. I am getting error when building my project:</p>
  
  <pre><code>ERROR in [at-loader] ./node_modules/@types/node/index.d.ts:82:15 
      TS2451: Cannot redeclare block-scoped variable 'custom'.
  ERROR in [at-loader] ./node_modules/@types/node/index.d.ts:85:15 
      TS2451: Cannot redeclare block-scoped variable 'custom'.
  ERROR in [at-loader] ./node_modules/@types/node/ts3.2/util.d.ts:7:15 
      TS2451: Cannot redeclare block-scoped variable 'custom'.
  ERROR in [at-loader] ./node_modules/@types/node/ts3.2/util.d.ts:10:15 
      TS2451: Cannot redeclare block-scoped variable 'custom'.
  </code></pre>
  
  <p>I initiated a complete new folder with just <code>typescript</code> and <code>@types/typescript</code> installed, I can still see the same error complained by <code>visual studio code</code>.</p>
  
  <p>Versions below:</p>
  
  <pre><code>  "dependencies": {
      "@types/node": "^11.13.6",
      "typescript": "^3.4.4"
    }
  </code></pre>
  
  <p>As the error showed above, I found</p>
  
  <p>in <code>index.d.ts</code>:</p>
  
  <pre><code>declare module "util" {
      namespace inspect {
          const custom: symbol;
      }
      namespace promisify {
          const custom: symbol;
      }
      namespace types {
          function isBigInt64Array(value: any): boolean;
          function isBigUint64Array(value: any): boolean;
      }
  }
  </code></pre>
  
  <p>in <code>util.d.ts</code>:</p>
  
  <pre><code>declare module "util" {
      namespace inspect {
          const custom: unique symbol;
      }
      namespace promisify {
          const custom: unique symbol;
      }
      namespace types {
          function isBigInt64Array(value: any): value is BigInt64Array;
          function isBigUint64Array(value: any): value is BigUint64Array;
      }
  }
  </code></pre>
  
  <p>We can see <code>custom</code> is indeed being re-declared in <code>index.d.ts</code> and <code>util.d.ts</code>.</p>
  
  <p>So my question is how to fix this issue? Is this a bug of @types/node?</p>