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.

No files, tests, or entry points are named, and the examples use Python while TiDB is a Go repository. First confirm how the reported broad error handling appears in this codebase, then identify the affected handlers and any existing tests. Done means in-scope handlers no longer swallow errors outside the cases they can safely handle, with relevant tests still passing.

Written by the indexing model from the issue text.