VST plugin: Editor crashes when the plugin does not provide a panel.

[theglobe]

In void VSTPluginInstance::startEditing(HWND hWnd, short* width, short* height), rect is used without checking that the plugin has initialized it, which leads to a crash when clicking "Open panel" for the plugin.

Some plugins do not implement a GUI and rely on the host to set the parameters for them or have no parameters to set.

See werman/noise-suppression-for-voice#44 for a workaround