```ts
export function applyOverrides(base: Record<string, string>, overrides: string[]): Record<string, string> {
    const result = { ...base };

    for (const override of overrides) {
        if (!Array.isArray(override) || typeof override !== 'string' || override.split('=').length !== 2) {
            throw new Error('Invalid override format');
        }

        const [name, value] = override.split('=');

        if (name === '' || !result.hasOwnProperty(name)) {
            throw new Error(`Override name '${name}' does not exist in base`);
        }

        result[name] = value;
    }

    return result;
}
```