Firebase function Http Trigger(POST) issue

I'm using Firebase function Http trigger (POST) request. Few requests are failing with below issue.

I understand some problem with JSON body parser, but don't know how to identify the exact POST request which is failing like this.

textPayload: "SyntaxError: Unexpected token 
 in JSON at position 274
    at Object.parse (native)
    at parse (/var/tmp/worker/node_modules/body-parser/lib/types/json.js:84:17)
    at /var/tmp/worker/node_modules/body-parser/lib/read.js:102:18
    at IncomingMessage.onEnd (/var/tmp/worker/node_modules/raw-body/index.js:149:7)
    at IncomingMessage.g (events.js:291:16)
    at emitNone (events.js:86:13)
    at IncomingMessage.emit (events.js:185:7)
    at endReadableNT (_stream_readable.js:974:12)
    at _combinedTickCallback (internal/process/next_tick.js:74:11)
    at process._tickDomainCallback (internal/process/next_tick.js:122:9)" 

Execution log of the above issue,

Function execution took 68 ms, finished with status code: 400
warning <SyntaxError: Unexpected token in JSON at position 274 at Object.parse (native) at parse.....>
Function execution started

Kindly help me on this..

via Karthi R