Description:
Starting around this week, OperaGX began creating a new, visible text file debug.log whenever it was used to open a PDF file. The content of the file suggests that it is the result of the browser's Chromium core producing a warning message. It is always created under the same path that the PDF is in, and will be created unless there isn't sufficient permission.

The image below shows the file (left) after opening a PDF (right):

The content within one of those files:

[0831/224114.810:ERROR:check.cc(290)] Check failed: false. NOTREACHED log messages are omitted in official builds. Sorry!

I suspect it coming from the Chromium core because this line can be found in Chromium's source code (check.cc):

void NotReachedError::TriggerNotReached() {
  // This triggers a NOTREACHED() error as the returned NotReachedError goes out
  // of scope.
  NotReached()
      << "NOTREACHED log messages are omitted in official builds. Sorry!";
}

This isn't a serious problem or anything, but it is weird that it just began showing up recently. Hopefully it's going to be an easy fix for the devs!

Steps to Reproduce:

1. Create a PDF file in a directory where Opera GX has permissions to read from and write to
2. Double-click the file to open it (typing file link in Opera GX will not reproduce the issue)
3. Navigate back to the folder where the PDF file is in. A new debug.log file should have been created with one line in it.

Note that reloading the PDF in Opera GX will also not create or update debug.log. If debug.log already exists in the right directory when opening a PDF, an additional line will be appended to it.

Expected Behavior: No debug.log file should be created, or at least visible to the user.

Edit: Issue persists in LVL 5 (core: 101.0.4843.81)