Fix: Handle vim.fn.getcompletion errors gracefully with pcall

[esmuellert]

Fix: Handle vim.fn.getcompletion errors gracefully

Problem

vim.fn.getcompletion() throws errors when the command line contains malformed or incomplete patterns. This is a common occurrence during normal typing and causes frequent crashes.

Reproduction cases:

1. Unmatched braces (Git users hit this constantly):

   :CodeDiff HEAD@{

   Error: E220: Missing }

2. Incomplete regex patterns:

   :grep /\(foo

   Error: E54: Unmatched \(

3. Other pattern errors:

   :grep /\(foo\)@<

   Error: E869: Unknown operator

Impact:

• Users see scary error messages during normal typing
• Completion stops working
• Poor user experience for very common use cases
• Multiple issues reported over 3 years (E220: Missing } error when typing :e { #73, Error when calling vim.fn.getcompletion() for cmdline has unfinished regex patterns #101)

Solution

Wrap vim.fn.getcompletion() with pcall() to catch errors gracefully.

Changes:

• 3 lines added, minimal change
• When getcompletion fails → return empty list (no crash)
• When getcompletion succeeds → normal behavior (no change)

Why this is the correct fix:

1. We cannot validate all possible malformed patterns beforehand
2. The patterns are incomplete while typing - this is expected behavior
3. Returning empty completion on error is the right UX
4. This was already proposed in Fix: try to get completion silently for invalid cmdline contents (#101) #102 but never merged

Testing

Before fix:

:lua vim.fn.getcompletion('e {', 'cmdline')
" E220: Missing }. (crash)

After fix:

:lua pcall(vim.fn.getcompletion, 'e {', 'cmdline')
" Returns: true, {} (no crash, empty results)

Related Issues

• Fixes E220: Missing } error when typing :e { #73 - E220: Missing } error (opened Nov 2022)
• Fixes Error when calling vim.fn.getcompletion() for cmdline has unfinished regex patterns #101 - Error with unfinished regex patterns (opened Jun 2023)
• Related to Fix: try to get completion silently for invalid cmdline contents (#101) #102 - Previous PR with same fix (closed without review)

Please Review

This is a simple, 3-line fix for a 3-year-old bug affecting many users in common workflows (Git commands, regex patterns, etc).

The fix has been tested by users and is already being used as a local workaround in the community.

Thank you for maintaining this essential plugin! 🙏

[dismint]

this would be an amazing fix, thank you for the work