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

  const result = { ...base };

  for (const override of overrides) {
    if (typeof override !== "string" || !override.includes("=")) {
      throw new Error("invalid override format");
    }

    const [name, value] = override.split("=", 2);
    if (name === "") {
      throw new Error("empty setting name");
    }
    if (!(name in result)) {
      throw new Error(`setting '${name}' not found in base`);
    }

    result[name] = value;
  }

  return result;
}
```