Consider accepting raw string as valid exception message

[saba-mo]

Hoist Core and Hoist React have some opinions that an exception will be returned over a json API with the following json forms:

// Hoist Core's incoming Exception shape, as parsed by JsonClient.groovy
{
     message?:string,
     className?: string
} 

// Hoist Core's outgoing Exception shape, as output by ThrowableSerializer.groovy
{
     name     : string,
     message  : string,
     isRoutine: boolean,
     cause?: string
}

// Hoist React's incoming exception shape, as parsed by ExceptionHandler.ts
{
     name: string, 
     message?: string
     isRoutine?: boolean
     ... 
} 

Is this too opinionated? Should we just accept a raw string in all cases as a valid exception message? This has come up recently in client apps.