Update DEV.md

Co-authored-by: Piotr Chabelski <ged.subfan@gmail.com>

DEV.md

@@ -7,10 +7,12 @@ Building Scala CLI requires JVM 17 to work properly.
 In theory, our build is able to download and install for its own needs JVM 17 on some OSes however it may not work in
 Intellij / Metals out of the box.
 
-When working with IntelliJ make sure that under `File -> Project Structure`:
+When working with IntelliJ make sure that the project's Java is set correctly.
+To confirm that, check under `File -> Project Structure`:
 - in `Project Settings/Project` `SDK` and `Language level` is set to **17**
 - in `Project Settings/Modules` all the modules have `Language level` set to **17**
 - in `Platform Settings/SDKs` only **Java 17** is visible
+Otherwise, some IDE features may not work correctly, i.e. the debugger might crash upon connection.
 
 The Scala CLI sources ship with Mill launchers, so that Mill itself doesn't need to be installed on your system.