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

* @property {boolean} [stopAtErrors] - Reject certain promises, e.g.
 *   `getOperatorList`, `getTextContent`, and `RenderTask`, when the associated
 *   PDF data cannot be successfully parsed, instead of attempting to recover
 *   whatever possible of the data. The default value is `false`.
 * @property {number} [maxImageSize] - The maximum allowed image size in total
 *   pixels, i.e. width * height. Images above this value will not be rendered.
 *   Use -1 for no limit, which is also the default value.
 * @property {boolean} [isEvalSupported] - Determines if we can evaluate strings
 *   as JavaScript. Primarily used to improve performance of font rendering, and
 *   when parsing PDF functions. The default value is `true`.
 * @property {boolean} [disableFontFace] - By default fonts are converted to
 *   OpenType fonts and loaded via `@font-face` rules. If disabled, fonts will
 *   be rendered using a built-in font renderer that constructs the glyphs with
 *   primitive path commands. The default value is `false`.
 * @property {boolean} [fontExtraProperties] - Include additional properties,
 *   which are unused during rendering of PDF documents, when exporting the
 *   parsed font data from the worker-thread. This may be useful for debugging
 *   purposes (and backwards compatibility), but note that it will lead to
 *   increased memory usage. The default value is `false`.
 * @property {HTMLDocument} [ownerDocument] - Specify an explicit document
 *   context to create elements with and to load resources, such as fonts,
 *   into. Defaults to the current document.
 * @property {boolean} [disableRange] - Disable range request loading of PDF
 *   files. When enabled, and if the server supports partial content requests,
 *   then the PDF will be fetched in chunks. The default value is `false`.
 * @property {boolean} [disableStream] - Disable streaming of PDF file data.
 *   By default PDF.js attempts to load PDF files in chunks. The default value
 *   is `false`.
 * @property {boolean} [disableAutoFetch] - Disable pre-fetching of PDF file
 *   data. When range requests are enabled PDF.js will automatically keep