Live share extension on the host side is using the startDebugging method to launch a debug configuration remotely. As part of step it will eventually need to invoke a task to build that could fail, the problem is that the API will not report 'false' value during the invocation.
Extract of the code here:

const result = await vscode.debug.startDebugging(folders ? folders[0] : undefined, debugConfiguration);
if (!result) {
// THIS code almost never get invoked....
throw new Error(Failed to launch debug configuration:${debugConfiguration.name});
}

we would like a better mechanism to know what really happen in our launch invocation.
Maybe knowing:

• If the build task was cancelled
• task failed
• Debug configuration is invalid
• Failure to launch

Adding a new richer method may be better...