Created attachment 128508 [details]
test case

SUMMARY

My PlasmaCore.DataSource identified by id=dataSource initially has four elements
connectedSources : ["date --date='@20000000000'", "date --date='@20000000001'", "date --date='@20000000002'", "date --date='@20000000003'"]

I get rid of the first element by:
dataSource.connectedSources.splice(0,1)
and afterwards dataSource.connectedSources gets corrupted.


STEPS TO REPRODUCE
1. download and unpack my test case
2. run install-and-run-plasmoid.sh in konsole
3. look for the console output

OBSERVED RESULT
connectedSources contains:
date --date='@20000000001',date --date='@20000000001',date --date='@20000000003'


EXPECTED RESULT
connectedSources should contain:
date --date='@20000000001',date --date='@20000000002',date --date='@20000000003'


SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora 32
KDE Plasma Version: 5.18.3
KDE Frameworks Version: 5.68
Qt Version: 5.13.2