It's a crux: just one letter in lower case instead of upper case, a missing bracket, a tiny typo, and nothing works anymore without a message from the Typo3 backend.
It would also be of great help if key words in the configuration language were highlighted in color and thus distinguishable from your own terms.
And of course auto-complete would be great!
Which extensions can help and are recommended?
Searching in the Extension Marketplace inside Visual Studio Code "TypoScript" shows the extension vscode-typo3-typoscript by Benjamin Kott. He's also a repository for it, which is also linked in that extension.
The last update is already some time ago and it should likely be updated.
There is still another TypoScript extension but the last update is longer time ago than of that above.
As you never wrote TypoScript but TYPO3 in general:
There is also an extension with Code Snippets for TYPO3, the identifier is ralffreit.typo3snippets and it's shown as "TYPO3 Code Snippets".