How to handle the error while passing when http post in flutter to python server

This is the code in my api.

from flask import Flask, request, redirect, url_for, flash, jsonify
import numpy as np
import joblib

app = Flask(__name__)

model = joblib.load('concrete-predicter.joblib')

@app.route('/', methods=['POST', 'GET'])
def feedModel():
    print("backend started")

    newdata = request.get_json('input')
    print(newdata)
    newDataArr = newdata['input'].split()
    data = [
        [float(newDataArr[0]), float(newDataArr[1]), float(newDataArr[2]), float(newDataArr[3]), float(newDataArr[4]),
         float(newDataArr[5]), float(newDataArr[6]), float(newDataArr[7])]]
    prediction = np.array2string(model.predict(data)[0])
    print(prediction)
    return jsonify(prediction)


if __name__ == '__main__':
    app.run(port=5000, debug=True)  # change to '0.0.0.0' your IPv4 address


    #array['output']=prediction

Further this is the flutter code snippet

onPressed: () async {
                          var input =
                              "540.0 0.0 0.0 162.0 2.5 1040.0 676.0 28"; //Input string
                          
                          final url = 'http://127.0.0.1:5000/';
                          final response = await http.post(
                              Uri.parse(url),
                              body: json.encode(
                                {
                                  'input': input
                                },
                              ),
                          );
                       },

In the server it shows "Bad Request Failed to decode JSON object: Expecting value: line 1 column 1 (char 0)" this error.

However in the server I can get the value but its showing a error and not running to the next code line in dart.

In flutter project's shown error is given bellow.

Error: XMLHttpRequest error.
    C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/core_patch.dart 910:28                get current
packages/http/src/browser_client.dart 69:22                                                                                    <fn>
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/zone.dart 1685:54                                              runUnary
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/future_impl.dart 159:18                                        handleValue
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/future_impl.dart 766:44                                        handleValueCallback
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/future_impl.dart 795:13                                        _propagateToListeners
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/future_impl.dart 592:7                                         [_complete]
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/stream_pipe.dart 61:11                                         _cancelAndValue
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/async/stream.dart 1288:7                                             <fn>
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 334:14  _checkAndCall
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 339:39  dcall
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/html/dart2js/html_dart2js.dart 37301:58                              <fn>


    at Object.createErrorWithStack (http://localhost:13265/dart_sdk.js:5080:12)
    at Function._throw (http://localhost:13265/dart_sdk.js:20337:18)
    at Function.throwWithStackTrace (http://localhost:13265/dart_sdk.js:20334:18)
    at async._AsyncCallbackEntry.new.callback (http://localhost:13265/dart_sdk.js:40851:18)
    at Object._microtaskLoop (http://localhost:13265/dart_sdk.js:40708:13)
    at _startMicrotaskLoop (http://localhost:13265/dart_sdk.js:40714:13)
    at http://localhost:13265/dart_sdk.js:36191:9