Fix SSE errors not logging correctly

Author: code-asher

src/api-helper.ts

@@ -1,11 +1,15 @@
+import { isApiError, isApiErrorResponse } from "coder/site/src/api/errors"
 import { Workspace, WorkspaceAgent } from "coder/site/src/api/typesGenerated"
 import { z } from "zod"
 
 export function errToStr(error: unknown, def: string) {
   if (error instanceof Error && error.message) {
     return error.message
-  }
-  if (typeof error === "string" && error.trim().length > 0) {
+  } else if (isApiError(error)) {
+    return error.response.data.message
+  } else if (isApiErrorResponse(error)) {
+    return error.message
+  } else if (typeof error === "string" && error.trim().length > 0) {
     return error
   }
   return def

src/workspaceMonitor.ts

@@ -63,8 +63,8 @@ export class WorkspaceMonitor implements vscode.Disposable {
       }
     })
 
-    eventSource.addEventListener("error", (error) => {
-      this.notifyError(error)
+    eventSource.addEventListener("error", (event) => {
+      this.notifyError(event.data)
     })
 
     // Store so we can close in dispose().
@@ -184,7 +184,7 @@ export class WorkspaceMonitor implements vscode.Disposable {
   private notifyError(error: unknown) {
     const message = errToStr(error, "No error message was provided")
     this.storage.writeToCoderOutputChannel(message)
-    vscode.window.showErrorMessage(`Failed to monitor workspace: ${message}`)
+    vscode.window.showErrorMessage(`Got error while monitoring workspace: ${message}`)
   }
 
   private updateContext(workspace: Workspace) {