Problems

Unnecessary complexity
Confusing logic
Hidden bugs
Harder maintenance
Slower performance
Cluttered Code

Solutions

Simplify checks
Trust your logic
Focus on essentials
Follow the K.I.S.S. principle
Refactor regularly

Context

Overthinking and overdesigning your code can lead to unnecessary complexity.

You might need to defend against every possible scenario, but this approach often produces bloated, confusing code.

Hanlon's Razor suggests that you should not assume malice when simple mistakes or misunderstandings are more likely.

Avoid overly defensive programming and focus on clear, straightforward logic.

You might anticipate future problems that might never happen or try to make your code too flexible.

Simple code is easier to maintain, debug, and understand.

Sample Code

Wrong

function processData(data) {
    if (typeof data === 'undefined') {
        throw new Error('Data is undefined');
    }

    if (typeof data !== 'object') {
        throw new Error('Data is not an object');
    }

    if (data === null) {
        throw new Error('Data is null');
    }

    if (Array.isArray(data)) {
        throw new Error('Data should not be an array');
    }

    if (!data.hasOwnProperty('items')) {
        return [];
    }

    if (!Array.isArray(data.items)) {
        throw new Error('Items should be an array');
    }

    if (data.items.length === 0) {
        return []; 
    }

    let processedItems = [];
    for (let item of data.items) {
        if (typeof item === 'undefined') {
            continue; // Skip undefined items
        }

        if (typeof item !== 'object') {
            continue; // Skip non-object items
        }

        if (item === null) {
            continue; // Skip null items
        }

        processedItems.push(processItem(item));
    }

    return processedItems;
}

Right

function processData(data) {
    if (!Array.isArray(data.items)) {
        throw new Error('Invalid data');
    }

    return data.items
        .filter(item => typeof item === 'object' && item !== null)
        .map(item => processItem(item));
}