Front sprocket chain guide

[Novice]

Hi advise needed again, I have a 20in folding ebike 13 months old. Both bikes have suffered broken magnet speed sensor discs I don’t know how except def not chain coming off.
I have realised if the chain did come off front sprocket it would destroy the disc.
I have seen bikes with double plastic chain guide on front sprocket, could I retro fit this would anyone recommend doing so? or am I being too cautious?
Thanks to all who reply and apologies for long winded question.

 

[Novice]

Hi, they are both Oxygen go’s. 7 speed.

 

[Novice]

I would just keep 46T, just would like to protect magnet disc the best I can

 

[Novice]

The plastic you see is a guard for your leg. The disc as in your pics is on the inside of of the chainring.