Add validation for configuration items of launch.json #355
Description
The debugger only has type validation for the config items (mainClass, projectName) of launch.json, this is a kind of static validation, and it cannot check the illegal value.
For example, for the common config errors below, the debugger will report it at a much latter stage with error message Failed to resolve classpath: .... It doesn't point out the failure reason clearly.
- Main class 'C:\demo\org\microsoft\app\Main.java' doesn't exist in the workspace.
- Main class 'org.microsoft.app.Main' isn't unique in the workspace.
- The project 'demo' is not a valid java project.
In order to better remind the user about the config error with more concise error message, plan to add code validation in the debug configuration provider for the key configuration items. (e.g. mainClass, projectName, port)