JavaScript
Module Not Found in Vite but Fine in Webpack
Same code, same package.json, different bundler, different result. The difference is resolution conditions and how strict each tool is.
Node.js
ERR_REQUIRE_ESM: The Complete Guide to Why Your Import Broke
The error that shows up when a dependency goes ESM only. What it means, the five ways to fix it, and how to pick the right one.
Networking
redirect_uri_mismatch and the Rest of OAuth Debugging
OAuth errors are unhelpful by design, because detailed errors would help attackers too. Here is how to work out what is actually wrong.
DevOps
Structured Logging, and What to Actually Put in a Log Line
Most logs are unqueryable prose written for a human who will never read them. Here is what makes a log line useful during an incident.
AI
Debugging an MCP Server When the Agent Just Goes Quiet
Your tool is registered, the agent knows it exists, and nothing happens. Here is how to see what is actually crossing the wire.
Networking
429 Too Many Requests: Both Sides of Rate Limiting
How to handle being rate limited without making it worse, and how to implement limits that do not punish well behaved clients.
Networking
Your Timeouts Are Wrong and Here Is How to Set Them
A missing timeout turns a slow dependency into an outage. A badly chosen one turns a blip into a retry storm. Both are common.
Performance
Where Serverless Cold Start Time Actually Goes
Everyone blames the platform. Most of a cold start is usually your own initialisation code, and you can measure exactly which part.
AI
The Package Your AI Assistant Recommended Does Not Exist
Models invent plausible package names. Attackers register them. Here is why this attack works and the two checks that stop it.
Node.js
EADDRINUSE: Finding and Killing Whatever Took Your Port
Address already in use. Here is how to find the process, why it sometimes is not a process at all, and why the port stays busy after you kill it.
JavaScript
Maximum Call Stack Size Exceeded When It Is Not Recursion
Sometimes it is infinite recursion. Often it is spreading a large array into a function call, and the fix is completely different.
JavaScript
Unexpected token < in JSON at position 0 Means You Got HTML
The angle bracket is the first character of an HTML error page. Your API returned a page, not JSON, and here is how to find out which page.