🐛 Bug Report: Server Error on Empty Function Entrypoint

### 👟 Reproduction steps 1. Create a New Function 2. Add the Name, Select Runtime > Next 3. Upload a `code.tar.gz` > Don't specify Entrypoint > Next 4. Set your Execute Permissions > Create 5. Server Error Stacktrace : ``` 2024-04-29 21:13:35 [Error] Method: POST 2024-04-29 21:13:35 [Error] URL: /v1/functions 2024-04-29 21:13:35 [Error] Type: TypeError 2024-04-29 21:13:35 [Error] Message: {closure}(): Argument #10 ($entrypoint) must be of type string, null given, called in /usr/src/code/vendor/utopia-php/framework/src/App.php on line 531 2024-04-29 21:13:35 [Error] File: /usr/src/code/app/controllers/api/functions.php 2024-04-29 21:13:35 [Error] Line: 171 ``` --- This wasn't the case on pre `1.5.x` if I am not wrong. We should probably use an empty string as a default as one is already used during executions, see [here](https://github.com/appwrite/appwrite/blob/c7bdcda59371f2b4db92a45ef0f7ba430a150792/app/controllers/api/functions.php#L1720C17-L1720C73). --- I am open to contributing to this if assigned. ### 👍 Expected behavior Process the deployment like the previous versions, assuming `index.js` as the default entrypoint. ### 👎 Actual Behavior Server Error. ### 🎲 Appwrite version Appwrite Cloud ### 💻 Operating system MacOS ### 🧱 Your Environment _No response_ ### 👀 Have you spent some time to check if this issue has been raised before? - [X] I checked and didn't find similar issue ### 🏢 Have you read the Code of Conduct? - [X] I have read the [Code of Conduct](https://github.com/appwrite/.github/blob/main/CODE_OF_CONDUCT.md)