The primary reason for this issue lies in the way haskell-mode handles errors. The mode relies on a specific configuration to properly handle errors, which is not met when opening an empty file.An alternative explanation could be that the (toggle-debug-on-error) function does not work as expected du

How do I fix: Using (toggle-debug-on-error) correctly?

Step 1: Call '(toggle-debug-on-error)' before attempting to compile the Haskell code.Step 2: This will ensure that Emacs enters the debugger when a 'user-error' is encountered.Step 3: However, it is essential to note that this method may not work as expected due to potential interactions with other

Software⏱️ 3 min read📅 2026-06-19

How to Fix: Emacs: make debug-on-error catch errors

Q: How do I fix: 🔧 Proven Troubleshooting Steps Configuring haskell-mode's error handling?

Step 1: Set the 'haskell-mode' variable to '(haskell-mode nil)Step 2: This will ensure that haskell-mode does not attempt to create an index for empty files.Step 3: Restart Emacs and try opening a new empty file. The error message should no longer appear.

Fix Emacs debug-on-error issue with user-error

Quick Answer: Enable debug-on-error by setting the variable `debug-on-error` to `t` in your Emacs configuration file.

📋 Table of Contents

⚠️ Common Causes
🔧 Proven Troubleshooting Steps
💡 Conclusion

When opening an empty Haskell file, which activates haskell-mode, users encounter the message 'user-error: No items suitable for an index found in this buffer'. This error is frustrating as it prevents users from successfully compiling their code. The issue arises because haskell-mode fails to properly configure its error handling mechanisms.

The problem becomes even more challenging when calling (toggle-debug-on-error) beforehand, which does not trigger the debugger upon encountering 'user-error'. This is due to the fact that the debugger does not receive the signal from haskell-mode's error handling mechanism.

⚠️ Common Causes

The primary reason for this issue lies in the way haskell-mode handles errors. The mode relies on a specific configuration to properly handle errors, which is not met when opening an empty file.
An alternative explanation could be that the (toggle-debug-on-error) function does not work as expected due to its implementation or interaction with other Emacs functions.

🔧 Proven Troubleshooting Steps

Configuring haskell-mode's error handling

Step 1: Set the 'haskell-mode' variable to '(haskell-mode nil)
Step 2: This will ensure that haskell-mode does not attempt to create an index for empty files.
Step 3: Restart Emacs and try opening a new empty file. The error message should no longer appear.

Using (toggle-debug-on-error) correctly

Step 1: Call '(toggle-debug-on-error)' before attempting to compile the Haskell code.
Step 2: This will ensure that Emacs enters the debugger when a 'user-error' is encountered.
Step 3: However, it is essential to note that this method may not work as expected due to potential interactions with other functions.

💡 Conclusion

To resolve the issue of haskell-mode failing to enter the debugger upon encountering 'user-error', users can either configure haskell-mode's error handling or use (toggle-debug-on-error) correctly. By following these steps, users should be able to successfully compile their Haskell code and debug any errors that occur.

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