How to trace runtime errors in Replit

1# This code will produce a traceback:
2def calculate_total(items):
3    total = 0
4    for item in items:
5        total += item['price'] * item['quantity']
6    return total
7
8orders = [
9    {'price': 10, 'quantity': 2},
10    {'price': 25},  # Missing 'quantity' key!
11]
12
13result = calculate_total(orders)
14
15# Traceback output:
16# Traceback (most recent call last):
17#   File "main.py", line 12, in <module>
18#     result = calculate_total(orders)
19#   File "main.py", line 4, in calculate_total
20#     total += item['price'] * item['quantity']
21# KeyError: 'quantity'

1# NameError — typo in variable name:
2user_name = "Alice"
3print(username)  # NameError: name 'username' is not defined
4
5# TypeError — wrong data type:
6age = "25"
7result = age + 10  # TypeError: can only concatenate str to str
8
9# KeyError — missing dictionary key:
10user = {'name': 'Alice'}
11print(user['email'])  # KeyError: 'email'
12
13# AttributeError — wrong method on wrong type:
14my_list = [1, 2, 3]
15my_list.split(',')  # AttributeError: 'list' has no attribute 'split'
16
17# IndexError — list index out of range:
18items = ['a', 'b', 'c']
19print(items[5])  # IndexError: list index out of range

1import logging
2
3# Set up logging with timestamps and severity levels
4logging.basicConfig(
5    level=logging.DEBUG,
6    format='%(asctime)s [%(levelname)s] %(message)s',
7    datefmt='%H:%M:%S'
8)
9
10def fetch_user(user_id):
11    logging.info(f"Fetching user {user_id}")
12    
13    if not isinstance(user_id, int):
14        logging.error(f"Invalid user_id type: {type(user_id).__name__}")
15        return None
16    
17    # Simulate database lookup
18    users = {1: 'Alice', 2: 'Bob'}
19    user = users.get(user_id)
20    
21    if user is None:
22        logging.warning(f"User {user_id} not found")
23    else:
24        logging.info(f"Found user: {user}")
25    
26    return user
27
28fetch_user(1)    # INFO: Found user: Alice
29fetch_user(99)   # WARNING: User 99 not found
30fetch_user('x')  # ERROR: Invalid user_id type: str

1import logging
2import json
3
4logging.basicConfig(
5    level=logging.DEBUG,
6    format='%(asctime)s [%(levelname)s] %(message)s'
7)
8
9def process_api_response(raw_data):
10    try:
11        data = json.loads(raw_data)
12        user_name = data['user']['name']
13        logging.info(f"Processed user: {user_name}")
14        return user_name
15    except json.JSONDecodeError as e:
16        logging.error(f"Invalid JSON response: {e}")
17        return None
18    except KeyError as e:
19        logging.error(f"Missing key in response: {e}")
20        return None
21    except Exception as e:
22        logging.exception(f"Unexpected error processing response")
23        return None
24
25# Test with valid data:
26process_api_response('{"user": {"name": "Alice"}}')
27
28# Test with invalid JSON:
29process_api_response('not json')
30
31# Test with missing key:
32process_api_response('{"user": {}}')

1import sys
2import traceback
3import logging
4
5logging.basicConfig(level=logging.DEBUG, format='%(asctime)s [%(levelname)s] %(message)s')
6
7def risky_operation():
8    data = {'a': 1}
9    return data['b']  # Will raise KeyError
10
11try:
12    risky_operation()
13except Exception:
14    exc_type, exc_value, exc_tb = sys.exc_info()
15    
16    logging.error(f"Exception type: {exc_type.__name__}")
17    logging.error(f"Exception message: {exc_value}")
18    
19    # Get the full traceback as a string
20    tb_lines = traceback.format_exception(exc_type, exc_value, exc_tb)
21    full_traceback = ''.join(tb_lines)
22    logging.error(f"Full traceback:\n{full_traceback}")
23    
24    # Extract the specific file and line number
25    tb_details = traceback.extract_tb(exc_tb)
26    for filename, line, func, text in tb_details:
27        logging.error(f"  File: {filename}, Line: {line}, Function: {func}")
28        logging.error(f"  Code: {text}")