Hi @johndg. Thanks for giving the beta phase Arduino IDE 2.x a try and proving your valuable feedback!
There are a lot of known issues with the Arduino Language Server that generates these underlines. You can see the list currently tracked by the IDE developers here:
The important thing to understand is that this is a different system from the one that compiles your code. As long as you can successfully compile, then the code is valid.
Just today, the developers made a nice improvement to the error messages to make them less cryptic;
Let's start with the full output. There is probably additional valuable information that will help us to identify the problem.
Please do this:
- Right click on the black "Output" pane at the bottom of the Arduino IDE 2.x window.
- From the context menu, click Copy All.
- Open a forum reply here by clicking the Reply button.
- Click the
</>icon on the post composer toolbar. This will add the forum's code block markup (```) to your reply to make sure the error messages are correctly formatted.
- Press Ctrl+V. This will paste the compilation output into the code block.
- Move the cursor outside of the code tags before you add any additional text to your reply.
- Click the Reply button to post the output.