src/vs/workbench/contrib/debug/common/debugModel.ts/DebugModel/sourceIsNotAvailable
class DebugModel:	sourceIsNotAvailable(uri: uri): void {
		this.sessions.forEach(s => {
			const source = s.getSourceForUri(uri);
			if (source) {
				source.available = false;
			}
		});
		this._onDidChangeCallStack.fire(undefined);
	}