Cannot create a panel on a dashboard with the pre-release v0.4.0

[fmassot]

An error occurred within the plugin
Object
status:500
statusText:"Internal Server Error"
data:Object
message:"An error occurred within the plugin"
messageId:"plugin.downstreamError"
statusCode:500
traceID:""
config:Object
url:"api/ds/query?ds_type=quickwit-quickwit-datasource&requestId=Q100"
method:"POST"
data:Object
requestId:"Q100"
hideFromInspector:false
headers:Object
retry:0
traceId:undefined
message:"An error occurred within the plugin"

[ddelemeny]

According to my tests, there is a 500 error happening at the panel editor initialization, but it doesn't prevent panel creation nor dashboard save.
It seems that the init query sent when creating a new panel is faulty, probably something mishandled in the query editor state management.
Needs further analysis.