Phoenix IDE freezes when opening large single-line JSON file with 300k+ columns

[charlypa]

Describe the bug

When attempting to open a JSON file containing a single line with more than 300,000 columns, Phoenix becomes non-responsive. After force-closing Phoenix, subsequent launches automatically reopen the same large file, causing the IDE to freeze again and making it completely unusable.

Reproduction

1. Create or obtain a JSON file containing a single line with 300,000+ columns
2. Open Phoenix IDE
3. Open the large JSON file
4. Observe Phoenix becoming unresponsive
5. Force-close Phoenix
6. Attempt to reopen Phoenix IDE

Expected behavior

Phoenix should either:

• Successfully open and handle large single-line JSON files
• Gracefully warn users about file size limitations
• Provide an option to prevent automatic reopening of problematic files from previous sessions

OS, Browser and Phoenix versions

Saw it in Linux ubuntu

logs or debug stack trace if any

No response

Additional context

This issue creates a feedback loop where Phoenix becomes unusable because it continuously attempts to reopen the problematic file on startup. The only current workaround is to manually delete Phoenix's session data to prevent it from reopening the file