React app connecting to API throws error

Hi All,
My react team is connecting to the API which I have crated using Apache Camel.
For success response everything works very well.
So all 200 responses are getting treated very well, React front ends gets the response entirely.
But once there is an error, e.g. with status code 400 - React Front end is not getting the response. In response I am sending an error msg.
I searched a lot over the internet, could not get any reliable solution.
Can any one please explain what exactly going wrong here ?

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