Whenever dev-ui is accessed while the data-index is still booting, this error happens:

Uncaught Error: Callback not found for [object Object]
    at e.callback (index.js:1:4447)
    at e.receive (index.js:1:5711)
    at Object.receive (index.js:1:2871)
    at e.receive (index.js:1:7373)
    at listener (standalone.ts:172:20)
workflowInstances:1 Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'apply')
    at e.receive (index.js:1:5420)
    at Object.receive (index.js:1:2871)
    at e.receive (index.js:1:7508)
    at eventListener.eventListener (index.js:1:6828)
index.js:1 Uncaught Error: Callback not found for [object Object]
    at e.callback (index.js:1:4447)
    at e.receive (index.js:1:5711)
    at Object.receive (index.js:1:2871)
    at e.receive (index.js:1:7508)
    at eventListener.eventListener (index.js:1:6828)
:8180/graphql:1     Failed to load resource: net::ERR_EMPTY_RESPONSE
3index.js:1 Uncaught Error: Callback not found for [object Object]
    at e.callback (index.js:1:4447)
    at e.receive (index.js:1:5711)
    at Object.receive (index.js:1:2871)
    at e.receive (index.js:1:7508)
    at eventListener.eventListener (index.js:1:6828)

 
In this scenario, a more specific message should be shown instead of the generic "Error fetching data error":

Title: Could not connect to data index
Subtitle: It is possible the data index is still being loaded, please try again in a few moments.