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

warn(`Error during font loading: ${exportedError}`);
            this.commonObjs.resolve(id, exportedError);
            break;
          }
          let fontRegistry = null;
          if (params.pdfBug && globalThis.FontInspector?.enabled) {
            fontRegistry = {
              registerFont(font, url) {
                globalThis.FontInspector.fontAdded(font, url);
              },
            };
          }
          const font = new FontFaceObject(exportedData, {
            isEvalSupported: params.isEvalSupported,
            disableFontFace: params.disableFontFace,
            ignoreErrors: params.ignoreErrors,
            onUnsupportedFeature: this._onUnsupportedFeature.bind(this),
            fontRegistry,
          });
          this.fontLoader
            .bind(font)
            .catch(reason => {
              return messageHandler.sendWithPromise("FontFallback", { id });
            })
            .finally(() => {
              if (!params.fontExtraProperties && font.data) {