Failed to resize horizontally/vertically at ApplyLayout when children sits alongside a plugin pane in a vertical split

Issue description

Failed to resize horizontally, attempting to first resize vertically / Failed to resize vertically, will not attempt again fires at ApplyLayout whenever a plugin pane sits inside a pane split_direction="vertical" { ... } block alongside the children placeholder. Swapping children for a bare pane in the exact same spot makes the warning disappear entirely.

This is plugin-agnostic — reproduced with zellij's own built-in zellij:status-bar/zjstatus, no third-party wasm needed — but at least one third-party plugin (zj-radar) actually crashes when it hits this unresolved resize state: marktoda/zj-radar#46. That crash is a separate bug in how that plugin reacts to it; this issue is about the resize failure itself, which happens regardless of which plugin is in the split.

Minimal reproduction

zellij --debug -l repro.kdl with:

layout {
    default_tab_template {
        pane size=2 borderless=true {
            plugin location="zellij:status-bar"
        }
        pane split_direction="vertical" {
            pane size=32 borderless=true {
                plugin location="zjstatus" {
                    format_left "{mode}"
                }
            }
            children
        }
    }
    tab focus=true
}

(zjstatus can be swapped for any plugin; the built-in status-bar in the size=32 slot reproduces it too — the split geometry is what matters, not the specific plugin.)

Log (~/.cache/zellij/*/zellij-log/zellij.log) at ApplyLayout:

INFO  ScreenInstruction::ApplyLayout: applying layout for tab 0
WARN  Failed to resize horizontally, attempting to first resize vertically
ERROR Failed to resize vertically, will not attempt again.
WARN  Failed to resize horizontally, attempting to first resize vertically
ERROR Failed to resize vertically, will not attempt again.

(fires twice per session start — once for each split boundary in the tree, consistent across every reproduction)

Replacing children with pane in the same position removes both warnings, 10/10 batched runs.

Expected behavior

No resize warning/error for a layout that's structurally valid (fixed size=32 sidebar + an auto-sized sibling in a vertical split is a completely ordinary layout shape — it works fine when the sibling is a bare pane instead of children).

Environment

• zellij 0.45.1 (Arch Linux)
• Terminal window: not undersized (confirmed wide/tall enough; the warning is unrelated to terminal size — reproduces identically in an 80x24 default-size pty)

Related

• marktoda/zj-radar#46 — the plugin-crash symptom this resize failure leads to for that specific plugin