invalid jar setting and already open files lead into "cannot call split of undefined" in Hover provider

Description

It's happening, especially with the new version 0.7 where the jar setting has changed, when you open vscode and already have a file open (so you left vscode the last time without closing the open file first.

When now also kickass is not found (it was for me with 0.7 the first time, because the new setting could not resolve kickass on my machine), the onDidOpen event does not happen. Thus there is no source found/set in the projectmanager. When i now switch to settings and change the new jar setting to a valid value, kickass is found again, but will not set the source for the open file in the projectmanager. Thus "this.source" is undefined. If you now hover over some existing label, the hover provider tries to split the sourcelines (via getSourceLines) which then triggers the error.

Temporary workaround for users until this is fixed in the next version: change something in the open file and save (if autosave is off) or close/reopen the file (after making sure the kickass jar setting is correct)

A quick fix to prevent the error would be to change getSourceLines in Project.ts

from

        return StringUtils.splitIntoLines(this.source);

to

        return StringUtils.splitIntoLines(this.source || '');

but this will still make the hover provider not respond until the current file went through asminfo once again (by reopening it or changing/saving it).

A better/correct fix would be to iterate through all open asm files in vscode and trigger the asminfo process manually once for those files whenever the jar setting is changed.