After a recent introduction of per-package flycheck for JSON projects, the code assumed that `world.flycheck` indices matched `world.workspaces` indices. However, not all workspaces have flycheck enabled (e.g., JSON projects without a flycheck template configured), so the flycheck vector can be shorter than the workspaces vector. This caused an index-out-of-bounds panic when saving a file in a JSON project without flycheck configured: thread 'Worker' panicked at notification.rs: index out of bounds: the len is 0 but the index is 0 Fix by looking up the flycheck handle by its ID (which is the workspace index set during spawn) rather than using the workspace index directly as a vector index.