Bug: requst/response body may be not in json

[AndrewDryga]

VM4523:1 Uncaught SyntaxError: Unexpected token < in JSON at position 0
    at JSON.parse (<anonymous>)
    at W (app.js?e64552a…:60)
    at t.value (app.js?e64552a…:60)
    at m._renderValidatedComponentWithoutOwnerOrContext (app.js?e64552a…:24)
    at m._renderValidatedComponent (app.js?e64552a…:24)
    at m.performInitialMount (app.js?e64552a…:24)
    at mountComponent (app.js?e64552a…:24)
    at Object.mountComponent (app.js?e64552a…:8)
    at m.performInitialMount (app.js?e64552a…:24)
    at mountComponent (app.js?e64552a…:24)
```