Fix error when agent has no metadata

The problem is that we dispose the watcher, which removes it from the
array, but then immediately try to get it off the array.  It then throws
into the catch where it tries to get it off the array again to
dispose (again).

Use a local object instead of getting it off the array each time.

Author: code-asher

src/workspacesProvider.ts

@@ -11,9 +11,11 @@ export enum WorkspaceQuery {
   All = "",
 }
 
+type AgentWatcher = { dispose: () => void; metadata?: AgentMetadataEvent[] }
+
 export class WorkspaceProvider implements vscode.TreeDataProvider<vscode.TreeItem> {
   private workspaces: WorkspaceTreeItem[] = []
-  private agentWatchers: Record<WorkspaceAgent["id"], { dispose: () => void; metadata?: AgentMetadataEvent[] }> = {}
+  private agentWatchers: Record<WorkspaceAgent["id"], AgentWatcher> = {}
   private timeout: NodeJS.Timeout | undefined
   private visible = false
   private fetching = false
@@ -174,29 +176,35 @@ export class WorkspaceProvider implements vscode.TreeDataProvider<vscode.TreeIte
       },
     })
 
-    this.agentWatchers[agentId] = {
+    let disposed = false
+    const watcher: AgentWatcher = {
       dispose: () => {
-        delete this.agentWatchers[agentId]
-        agentMetadataEventSource.close()
+        if (!disposed) {
+          delete this.agentWatchers[agentId]
+          agentMetadataEventSource.close()
+          disposed = true
+        }
       },
     }
 
+    this.agentWatchers[agentId] = watcher
+
     agentMetadataEventSource.addEventListener("data", (event) => {
       try {
         const dataEvent = JSON.parse(event.data)
         const agentMetadata = AgentMetadataEventSchemaArray.parse(dataEvent)
 
         if (agentMetadata.length === 0) {
-          this.agentWatchers[agentId].dispose()
+          watcher.dispose()
         }
 
-        const savedMetadata = this.agentWatchers[agentId].metadata
-        if (JSON.stringify(savedMetadata) !== JSON.stringify(agentMetadata)) {
-          this.agentWatchers[agentId].metadata = agentMetadata // overwrite existing metadata
+        // Overwrite metadata if it changed.
+        if (JSON.stringify(watcher.metadata) !== JSON.stringify(agentMetadata)) {
+          watcher.metadata = agentMetadata
           this.refresh()
         }
       } catch (error) {
-        this.agentWatchers[agentId].dispose()
+        watcher.dispose()
       }
     })
   }