Fixed: Improved error handling for invalid JSON in global_config.json

[sammamama]

Fixed #1404 . A dialog box error now pops up for the people with invalid JSON in their global_config,json file.

Fixes:
I changed the code to throw an error, whenever an error is caught while trying to read global_config.json file.

Platforms this PR was tested on:

• Windows
• macOS
• Linux (specify distro)

Self-review checklist

• Self-reviewed the changes for clarity and maintainability
  (variable names, code reuse, readability, etc.).

Communicate decisions, questions, and potential concerns.

• Explains differences from previous plans (e.g., issue description).
• Highlights technical choices and bugs encountered.
• Calls out remaining decisions and concerns.
• Automated tests verify logic where appropriate.

Individual commits are ready for review (see commit discipline).

• Each commit is a coherent idea.
• Commit message(s) explain reasoning and motivation for changes.

Completed manual review and testing of the following:

• Visual appearance of the changes.
• Responsiveness and internationalization.
• Strings and tooltips.
• End-to-end functionality of buttons, interactions and flows.
• Corner cases, error conditions, and easily imagined bugs.

[alya]

Please clean up your commit history and post again to request a review. See here for guidelines.

I'm not sure why this PR is marked as a draft. In general, that is a signal that you don't want reviewers to look at it yet.

[sammamama]

I'll clean up my commit history.

I marked this as Draft as I though it was part of the guidelines. But since I now know it is not, I'll make it a PR.

[alya]

Please update your commit message to match the commit style guidelines.

[sammamama]

Fixed the commit message according to commit style guidelines.

[timabbott]

Closing in favor of #1425, thanks for the effort @sammamama!