Hi!
According to this issue http package should have been upgraded:
But trying v 1.1.2 it still persists although in your pubspec.yaml it says 1.2.
Because signalr_core <1.1.0 doesn't support null safety and signalr_core >=1.1.0 <1.1.2 depends on http ^0.13.0, signalr_core <1.1.2 requires http ^0.13.0.
And because flutter_svg >=2.0.10+1 depends on http ^1.0.0 and signalr_core >=1.1.2 requires SDK version ^3.2.6, flutter_svg >=2.0.10+1 is incompatible with signalr_core.
So, because joinorcreate_app depends on both flutter_svg ^2.0.10+1 and signalr_core any, version solving failed.