add a regression test for when engine returns a export fail (#3407)

* add a regression test for when engine returns a export fail

Signed-off-by: Jess Frazelle <github@jessfraz.com>

* better errors

Signed-off-by: Jess Frazelle <github@jessfraz.com>

---------

Signed-off-by: Jess Frazelle <github@jessfraz.com>

src/lang/std/engineConnection.ts

@@ -952,6 +952,7 @@ class EngineConnection extends EventTarget {
               ) {
                 // Reject the promise with the error.
                 this.engineCommandManager.pendingExport.reject(errorsString)
+                toast.error(errorsString)
                 this.engineCommandManager.pendingExport = undefined
               }
             } else {
@@ -1315,7 +1316,7 @@ export class EngineCommandManager extends EventTarget {
   commandLogs: CommandLog[] = []
   pendingExport?: {
     resolve: (a: null) => void
-    reject: (reason: any) => void
+    reject: (reason: string) => void
     commandId: string
   }
   settings: SettingsViaQueryString
@@ -1911,8 +1912,9 @@ export class EngineCommandManager extends EventTarget {
       const promise = new Promise<null>((resolve, reject) => {
         this.pendingExport = {
           resolve,
-          reject: () => {
+          reject: (reason: string) => {
             this.exportIntent = null
+            reject(reason)
           },
           commandId: command.cmd_id,
         }