When neither clone nor iso is set, apply ends with generic "VM not found" error

[andrzejressel]

To reproduce:

Try creating machine with following config:

resource "proxmox_vm_qemu" "cloudinit-test" {
	name = "tftest1.xyz.com"
	desc = "tf description"
	target_node = "pve"

	storage = "local"
	cores = 3
	sockets = 1
	memory = 2560
	disk_gb = 4
	nic = "virtio"
	bridge = "vmbr0"

	ssh_user = "root"
	ssh_private_key = <<EOF
-----BEGIN RSA PRIVATE KEY-----
private ssh key root
-----END RSA PRIVATE KEY-----
EOF

	os_type = "cloud-init"
	ipconfig0 = "ip=10.0.2.99, gw=10.0.2.2"

	sshkeys = <<EOF
ssh-rsa AAAAB3NzaC1kj...key1
ssh-rsa AAAAB3NzaC1kj...key2
EOF

	provisioner "remote-exec" {
		inline = [
			"ip a"
		]
	}
}

Actual:
tfstate with machine is created and proxmox_vm_qemu.cloudinit-test: Vm '101' not found error is shown

Expected:
tfstate is not created (at least not with that machine) and Machine must have either clone or iso set error is shown.