TreeView panics with 'index out of range' error

[urandom]

For some reason, during TreeView's process, the code tries to get a node outside the index. The problem is that the tree does not have any nodes yet.

The stack trace:

github.com/rivo/tview.(*Application).Run.func1(0xc000268f00)
	/home/urandom/.go/src/github.com/rivo/tview/application.go:149 +0x82
panic(0x114ba80, 0x1e28b80)
	/usr/lib/go/src/runtime/panic.go:522 +0x1b5
github.com/rivo/tview.(*TreeView).process(0xc000269000)
	/home/urandom/.go/src/github.com/rivo/tview/treeview.go:501 +0x432
github.com/rivo/tview.(*TreeView).Draw(0xc000269000, 0x146c160, 0xc0002416c0)
	/home/urandom/.go/src/github.com/rivo/tview/treeview.go:543 +0x931
github.com/rivo/tview.(*Flex).Draw(0xc0002cf0b0, 0x146c160, 0xc0002416c0)
	/home/urandom/.go/src/github.com/rivo/tview/flex.go:169 +0x290
github.com/rivo/tview.(*Flex).Draw(0xc0002cf050, 0x146c160, 0xc0002416c0)
	/home/urandom/.go/src/github.com/rivo/tview/flex.go:169 +0x290
github.com/rivo/tview.(*Pages).Draw(0xc0002cefc0, 0x146c160, 0xc0002416c0)
	/home/urandom/.go/src/github.com/rivo/tview/pages.go:246 +0xf1
github.com/rivo/tview.(*Application).draw(0xc000268f00, 0x0)
	/home/urandom/.go/src/github.com/rivo/tview/application.go:363 +0xd8
github.com/rivo/tview.(*Application).QueueUpdateDraw.func1()
	/home/urandom/.go/src/github.com/rivo/tview/application.go:494 +0x3d
github.com/rivo/tview.(*Application).Run(0xc000268f00, 0x0, 0x0)
	/home/urandom/.go/src/github.com/rivo/tview/application.go:253 +0x4dd

The simplest fix might be to return early from the process method if there are no nodes.

[rivo]

I'm having trouble following this stack trace. The line numbers don't seem to line up with the current code. And TreeView actually doesn't do anything if there is no root node, see here:

tview/treeview.go

Line 542 in 9d616ae

if t.root == nil {

Are you using the latest commit?

[urandom]

This is an up-to-date stack trace:

panic: runtime error: index out of range [recovered]
	panic: runtime error: index out of range

goroutine 1 [running]:
github.com/rivo/tview.(*Application).Run.func1(0xc000234d80)
	/home/urandom/.go/src/github.com/rivo/tview/application.go:149 +0x82
panic(0x1151140, 0x1e16ae0)
	/usr/lib/go/src/runtime/panic.go:522 +0x1b5
github.com/rivo/tview.(*TreeView).process(0xc000234e80)
	/home/urandom/.go/src/github.com/rivo/tview/treeview.go:506 +0x432
github.com/rivo/tview.(*TreeView).Draw(0xc000234e80, 0x1471320, 0xc000115340)
	/home/urandom/.go/src/github.com/rivo/tview/treeview.go:548 +0x931
github.com/rivo/tview.(*Flex).Draw(0xc00027aa80, 0x1471320, 0xc000115340)
	/home/urandom/.go/src/github.com/rivo/tview/flex.go:169 +0x290
github.com/rivo/tview.(*Flex).Draw(0xc00027aa20, 0x1471320, 0xc000115340)
	/home/urandom/.go/src/github.com/rivo/tview/flex.go:169 +0x290
github.com/rivo/tview.(*Pages).Draw(0xc00027a990, 0x1471320, 0xc000115340)
	/home/urandom/.go/src/github.com/rivo/tview/pages.go:262 +0xf1
github.com/rivo/tview.(*Application).draw(0xc000234d80, 0x0)
	/home/urandom/.go/src/github.com/rivo/tview/application.go:363 +0xd8
github.com/rivo/tview.(*Application).QueueUpdateDraw.func1()
	/home/urandom/.go/src/github.com/rivo/tview/application.go:494 +0x3d
github.com/rivo/tview.(*Application).Run(0xc000234d80, 0x0, 0x0)
	/home/urandom/.go/src/github.com/rivo/tview/application.go:253 +0x4dd

[urandom]

On further investigation there is at least one node in the tree at this point, and the tree is set to level 1, and has finished being updated with more nodes via a QueueUpdateDraw call (which causes the Draw call)

The panic itself is caused by the root node being set as current (via SetCurrentNode), while also being invisible, and not having any children

[rivo]

I made a change which I believe will fix the panic that you reported. Please have a look and let me know if it works now.

[urandom]

I can't seem to reproduce the problem with your latest change.