Assertion at "The host is misbehaving! The plugin must be deactivated before setting new arrangements."

I’m using JUCE v7.0.2, and when I close the plugin host (the JUCE Plug-In Host) or when I close the plugin, I get the following assertion, from line 3103 in juce_VST3_Wrapper.cpp:

    tresult PLUGIN_API activateBus (Vst::MediaType type,
                                    Vst::BusDirection dir,
                                    Steinberg::int32 index,
                                    TBool state) override
    {
        // The host is misbehaving! The plugin must be deactivated before setting new arrangements.
        jassert (! active);
       ...

There is only one line on the call stack, so what should I look for?

The call stack only lists:

>	none2.vst3!juce::JuceVST3Component::activateBus(long type, long dir, long index, unsigned char state) Line 3103	C++
>	[External Code]