Attach (recommended) or Link to PDF file here:
[issue13075.pdf](https://github.com/mozilla/pdf.js/files/6117265/issue13075.pdf)

Configuration:
- Web browser and its version: Node.js 14.15.5
- Operating system and its version: Mac OS 11.2.1
- PDF.js version: master/2.7.570/2.6.347/1.10.100
- Is a browser extension: false

Steps to reproduce the problem:
1. const fileBuffer = fs.readFileSync('./pdf')
2. PDFJS.getDocument(fileBuffer)
3. fileBuffer.buffer has junk data at the start and at the end. Randomly, pdfjs can not read a buffer, whose buffer.buffer contains random memory junk data in fileBuffer.buffer

What is the expected behavior? pdfjs ignores a buffer.buffer and reads only buffer

What went wrong? (add screenshot)
I've catched that random error and wrote fileBuffer.buffer of the error buffer to a file named issue13075.pdf
I've recreated a buffer that has the wrong buffer.buffer (see line 6). Pdfjs fails to read that buffer (console.log('Fail')).
The Uint8Array of that buffer, pdfjs correctly reads (console.log('OK')).
![image](https://user-images.githubusercontent.com/8398353/110660366-59f1a780-8178-11eb-94c2-29be826c2118.png)


codesandbox:
https://codesandbox.io/s/pdfjs-loading-from-buffer-issue-9h4fd?file=/src/index.js

*   fetching more data even if it isn't needed to display the current page.
 *   The default value is `false`.
 *
 *   NOTE: It is also necessary to disable streaming, see above, in order for
 *   disabling of pre-fetching to work correctly.
 * @property {boolean} [pdfBug] - Enables special hooks for debugging PDF.js
 *   (see `web/debugger.js`). The default value is `false`.
 */
/**
 * @typedef {Object} PDFDocumentStats
 * @property {Object<string, boolean>} streamTypes - Used stream types in the
 *   document (an item is set to true if specific stream ID was used in the
 *   document).
 * @property {Object<string, boolean>} fontTypes - Used font types in the
 *   document (an item is set to true if specific font ID was used in the
 *   document).
 */
/**
 * This is the main entry point for loading a PDF and interacting with it.
 *
 * NOTE: If a URL is used to fetch the PDF data a standard Fetch API call (or
 * XHR as fallback) is used, which means it must follow same origin rules,
 * e.g. no cross-domain requests without CORS.
 *
 * @param {string|TypedArray|DocumentInitParameters|PDFDataRangeTransport} src -
 *   Can be a URL to where a PDF file is located, a typed array (Uint8Array)
 *   already populated with data or parameter object.
 * @returns {PDFDocumentLoadingTask}
 */
function getDocument(src) {