InterpolatedCamera causes warnings in Godot's console and weird output behaviour

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:bust_in_silhouette: Asked By del
:warning: Old Version Published before Godot 3 was released.

as soon as I load my game project in the editor these error warnings are printed constantly in the console:
camera error

I think this is caused by my InterpolationCamera which is tracking another 3D camera, because when i delete the InterpolationCamera the warnings stops.
Also my output box gets filled with “empty prints” (as if i’m holding down enter in a text editor) as soon as I run the game.
Why is this? Could this slow down the game or something (cause it seems to me so)?