A single legal empty literal such as `fetch('')`, `require('')`,
`bus.on('', f)`, `localStorage.getItem('')`, or `ipcMain.handle('', f)`
made the whole application analysis fail with `unreadable_output`: the
literal became an application-graph observation label, an artifact-local
identity key, or a semantic node label, all of which must be nonempty.
Normalize display at the two graph construction seams instead of at each
producer: `JavaScriptArtifactGraphAccumulator.addNode` and
`constructSemanticGraphNode` show the empty value as `""` via a shared
`javascriptDisplayText` helper. Observation and node properties keep the
exact empty value. This replaces the per-site `semanticNameLabel` calls.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
