Link various screens accessible from the bridge

This kind of linking is starting to creak...

internal/ui/driver.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"image"
 	"log"
+	"runtime/debug"
 	"strconv"
 
 	"github.com/hajimehoshi/ebiten"
@@ -24,14 +25,10 @@ func init() {
 	registerBuilder(menus.TypeLineKbd, registerDebug("Unimplemented LineKbd", nil))
 	registerBuilder(menus.TypeDialogue, registerDebug("Unimplemented Dialogue", nil))
 
-	// Needed for Arrange.mnu (???)
-	registerBuilder(menus.TypeSquadButton, registerDebug("Unimplemented SquadButton", nil))
-
 	// Needed for Briefing.mnu
 	registerBuilder(menus.TypeLineBriefing, registerDebug("Unimplemented LineBriefing", nil))
 
 	// Needed for ChaEquip.mnu
-	registerBuilder(menus.TypeUnknown1, registerDebug("Unimplemented Unknown1", nil))
 	registerBuilder(menus.TypeThumb, registerDebug("Unimplemented Thumb", nil))
 
 	// Needed for MainGameChaos.mnu
@@ -226,6 +223,11 @@ func (d *Driver) SetValueInt(id string, value int) error {
 }
 
 func (d *Driver) Update(screenX, screenY int) error {
+	if d == nil {
+		debug.PrintStack()
+		return fmt.Errorf("Tried to update a nil ui.Driver")
+	}
+
 	// This will be updated while processing hovers
 	d.tooltip = ""
 	d.ticks += 1
@@ -274,6 +276,11 @@ func (d *Driver) Update(screenX, screenY int) error {
 }
 
 func (d *Driver) Draw(screen *ebiten.Image) error {
+	if d == nil {
+		debug.PrintStack()
+		return fmt.Errorf("Tried to draw a nil ui.Driver")
+	}
+
 	var do ebiten.DrawImageOptions
 
 	for _, paint := range d.paintables {