Exception type too broad in error handling

## Bug Report

### Description
Some `except` clauses catch overly broad exception types (e.g., bare `except:` or `except Exception:`), which can accidentally swallow important errors like `KeyboardInterrupt` or `SystemExit`.

### Example
```python
# Problematic:
try:
do_something()
except: # catches EVERYTHING including KeyboardInterrupt
pass

# Better:
try:
do_something()
except ValueError as e:
logger.warning(f"Value error: {e}")
```

### Expected Behavior
Exception handlers should catch only the specific exceptions they know how to handle.

### Impact
- Makes it impossible to interrupt the program with Ctrl+C in some cases
- Hides unexpected errors that should be investigated
- Makes debugging significantly harder

### Suggested Fix
Replace broad `except` clauses with specific exception types wherever possible.

The issue does not name any files, tests, or entry points, and its examples use Python `except` clauses while TiDB is a Go repository. First verify whether the reported pattern exists in the Go source and identify the affected locations; completion would require replacing only handlers whose intended exception scope is established and running the relevant tests.

Written by the indexing model from the issue text.