resource/aws_fsx_windows_file_system: Prevent potential panics, unexp…

…ected errors, and use correct operation timeout on update

Reference: https://docs.aws.amazon.com/fsx/latest/APIReference/API_AdministrativeAction.html
Reference: #16440

Output from acceptance testing:

```
Pending
```

aws/fsx.go

@@ -48,7 +48,7 @@ func refreshFsxFileSystemLifecycle(conn *fsx.FSx, id string) resource.StateRefre
 	}
 }
 
-func refreshFsxFileSystemLifecycleOptimizing(conn *fsx.FSx, id string) resource.StateRefreshFunc {
+func refreshFsxFileSystemAdministrativeActionsStatusFileSystemUpdate(conn *fsx.FSx, id string) resource.StateRefreshFunc {
 	return func() (interface{}, string, error) {
 		filesystem, err := describeFsxFileSystem(conn, id)
 
@@ -64,7 +64,17 @@ func refreshFsxFileSystemLifecycleOptimizing(conn *fsx.FSx, id string) resource.
 			return nil, "", nil
 		}
 
-		return filesystem, aws.StringValue(filesystem.AdministrativeActions[0].Status), nil
+		for _, administrativeAction := range filesystem.AdministrativeActions {
+			if administrativeAction == nil {
+				continue
+			}
+
+			if aws.StringValue(administrativeAction.AdministrativeActionType) == fsx.AdministrativeActionTypeFileSystemUpdate {
+				return filesystem, aws.StringValue(administrativeAction.Status), nil
+			}
+		}
+
+		return filesystem, fsx.StatusCompleted, nil
 	}
 }
 
@@ -110,14 +120,17 @@ func waitForFsxFileSystemUpdate(conn *fsx.FSx, id string, timeout time.Duration)
 	return err
 }
 
-func waitForFsxFileSystemUpdateOptimizing(conn *fsx.FSx, id string, timeout time.Duration) error {
+func waitForFsxFileSystemUpdateAdministrativeActionsStatusFileSystemUpdate(conn *fsx.FSx, id string, timeout time.Duration) error {
 	stateConf := &resource.StateChangeConf{
-		Pending: []string{fsx.StatusInProgress},
+		Pending: []string{
+			fsx.StatusInProgress,
+			fsx.StatusPending,
+		},
 		Target: []string{
 			fsx.StatusCompleted,
 			fsx.StatusUpdatedOptimizing,
 		},
-		Refresh: refreshFsxFileSystemLifecycleOptimizing(conn, id),
+		Refresh: refreshFsxFileSystemAdministrativeActionsStatusFileSystemUpdate(conn, id),
 		Timeout: timeout,
 		Delay:   30 * time.Second,
 	}

aws/resource_aws_fsx_windows_file_system.go

@@ -31,6 +31,7 @@ func resourceAwsFsxWindowsFileSystem() *schema.Resource {
 		Timeouts: &schema.ResourceTimeout{
 			Create: schema.DefaultTimeout(45 * time.Minute),
 			Delete: schema.DefaultTimeout(30 * time.Minute),
+			Update: schema.DefaultTimeout(45 * time.Minute),
 		},
 
 		Schema: map[string]*schema.Schema{
@@ -334,12 +335,13 @@ func resourceAwsFsxWindowsFileSystemUpdate(d *schema.ResourceData, meta interfac
 
 	if requestUpdate {
 		_, err := conn.UpdateFileSystem(input)
+
 		if err != nil {
-			return fmt.Errorf("error updating FSX File System (%s): %s", d.Id(), err)
+			return fmt.Errorf("error updating FSx Windows File System (%s): %w", d.Id(), err)
 		}
 
-		if err := waitForFsxFileSystemUpdateOptimizing(conn, d.Id(), d.Timeout(schema.TimeoutCreate)); err != nil {
-			return fmt.Errorf("Error waiting for filesystem (%s) to become available: %w", d.Id(), err)
+		if err := waitForFsxFileSystemUpdateAdministrativeActionsStatusFileSystemUpdate(conn, d.Id(), d.Timeout(schema.TimeoutUpdate)); err != nil {
+			return fmt.Errorf("error waiting for FSx Windows File System (%s) update: %w", d.Id(), err)
 		}
 	}
 

website/docs/r/fsx_windows_file_system.html.markdown

@@ -100,6 +100,7 @@ configuration options:
 
 * `create` - (Default `45m`) How long to wait for the file system to be created.
 * `delete` - (Default `30m`) How long to wait for the file system to be deleted.
+* `update` - (Default `45m`) How long to wait for the file system to be updated.
 
 ## Import