```ts
export function applyOverrides(base: Record<string, string>, overrides: string[]): Record<string, string> {
  if (!Array.isArray(overrides)) {
    throw new Error("Overrides must be a list.");
  }

  const merged = { ...base };

  for (const override of overrides) {
    const [name, value] = override.split('=', 2);

    if (!name || !value) {
      throw new Error("Each override must be a non-empty string with an equals sign.");
    }

    if (name === '') {
      throw new Error("Override name cannot be empty.");
    }

    if (!(name in base)) {
      throw new Error(`Base does not contain setting '${name}'.`);
    }

    merged[name] = value;
  }

  return merged;
}
```