[Bug]: Uncaught error on unexpected data after end of stream

[CyberAndrii]

Attach (recommended) or Link to PDF file

PDF_FILE-1.pdf

Web browser and its version

Chrome 129.0.6668.10 / Firefox 131.0

Operating system and its version

macOS Sonoma 14.6.1 / Ubuntu 22.04.5

PDF.js version

4.4.168

Is the bug present in the latest PDF.js version?

Yes

Is a browser extension

No

Steps to reproduce the problem

1. Go to https://jsfiddle.net/tr2h1j8f/
2. Open the DevTools console
3. Click the Run button

What is the expected behavior?

No errors should appear in the console.

What went wrong?

Chrome

The Uncaught (in promise) TypeError: Junk found after end of compressed data. error appears in the console.

Firefox

The TypeError: Unexpected input after the end of stream error appears in the console.

Link to a viewer

No response

Additional context

Related code:

pdf.js/src/core/flate_stream.js

Lines 157 to 197 in 233ac17

	async asyncGetBytes() {
	this.str.reset();
	const bytes = this.str.getBytes();
	try {
	const { readable, writable } = new DecompressionStream("deflate");
	const writer = writable.getWriter();
	writer.write(bytes);
	writer.close();
	const chunks = [];
	let totalLength = 0;
	for await (const chunk of readable) {
	chunks.push(chunk);
	totalLength += chunk.byteLength;
	}
	const data = new Uint8Array(totalLength);
	let offset = 0;
	for (const chunk of chunks) {
	data.set(chunk, offset);
	offset += chunk.byteLength;
	}
	return data;
	} catch {
	// DecompressionStream failed (for example because there are some extra
	// bytes after the end of the compressed data), so we fallback to our
	// decoder.
	// We already get the bytes from the underlying stream, so we just reuse
	// them to avoid get them again.
	this.str = new Stream(
	bytes,
	2 /* = header size (see ctor) */,
	bytes.length,
	this.str.dict
	);
	this.reset();
	return null;
	}
	}

This error occurs because promises returned by writer.write(bytes); and writer.close(); are not being awaited. There’s a reason for this though which is explained in whatwg/compression#55 (comment).

A potential solution could be to discard the errors

writer.write(bytes).catch(() => {});
writer.close().catch(() => {});

They will still be caught by the catch block when awaited here

pdf.js/src/core/flate_stream.js

Line 170 in 233ac17

for await (const chunk of readable) {