Merge branch '280-show-info-message-if-no-extension-key-is-registered' into 'develop'

Resolve "Show info message if no extension key is registered"

Closes #280

See merge request t3o/ter!579
8 jobs for develop in 7 minutes and 22 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Maintenance
manual #23665
allowed to fail manual
Get dump for local environment
 
  Test
passed #23668
test:composer

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passed #23667
test:php

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passed #23666
test:typoscript

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passed #23669
test:unit

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9.95%
 
  Build
passed #23670
build

00:01:04

 
  Layout
passed #23671
layout

00:01:32

 
  Deploy
passed #23672
deploy-develop

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