aerc: always check SelectedAccount return value

aerc.SelectedAccount() is used in lots of places. Most of them without
checking the return value.

In some cases, the currently selected tab is not related to any account
(widget.Terminal for example). This can lead to unexpected crashes when
accessing account specific configuration.

When possible, return an error when no account is currently selected.
If no error can be returned, fallback to non-account specific
configuration.

Signed-off-by: Robin Jarry <robin@jarry.cc>
Reviewed-by: Koni Marti <koni.marti@gmail.com>

3 files changed, 32 insertions, 22 deletions

diff --git a/widgets/aerc.go b/widgets/aerc.go
index 10e9924c..98bc1b23 100644
--- a/widgets/aerc.go
+++ b/widgets/aerc.go
@@ -309,6 +309,14 @@ func (aerc *Aerc) SelectedAccount() *AccountView {
 	return nil
 }
 
+func (aerc *Aerc) SelectedAccountUiConfig() config.UIConfig {
+	acct := aerc.SelectedAccount()
+	if acct == nil {
+		return aerc.conf.Ui
+	}
+	return acct.UiConfig()
+}
+
 func (aerc *Aerc) SelectedTab() ui.Drawable {
 	return aerc.tabs.Tabs[aerc.tabs.Selected].Content
 }
diff --git a/widgets/compose.go b/widgets/compose.go
index 7229ec84..e47aa3eb 100644
--- a/widgets/compose.go
+++ b/widgets/compose.go
@@ -127,15 +127,15 @@ func (c *Composer) buildComposeHeader(aerc *Aerc, cmpl *completer.Completer) {
 	c.layout = aerc.conf.Compose.HeaderLayout
 	c.editors = make(map[string]*headerEditor)
 	c.focusable = make([]ui.MouseableDrawableInteractive, 0)
+	uiConfig := aerc.SelectedAccountUiConfig()
 
 	for i, row := range c.layout {
 		for j, h := range row {
 			h = strings.ToLower(h)
 			c.layout[i][j] = h // normalize to lowercase
-			e := newHeaderEditor(h, c.header, aerc.SelectedAccount().UiConfig())
+			e := newHeaderEditor(h, c.header, uiConfig)
 			if aerc.conf.Ui.CompletionPopovers {
-				e.input.TabComplete(cmpl.ForHeader(h),
-					aerc.SelectedAccount().UiConfig().CompletionDelay)
+				e.input.TabComplete(cmpl.ForHeader(h), uiConfig.CompletionDelay)
 			}
 			c.editors[h] = e
 			switch h {
@@ -152,9 +152,9 @@ func (c *Composer) buildComposeHeader(aerc *Aerc, cmpl *completer.Completer) {
 	for _, h := range []string{"cc", "bcc"} {
 		if c.header.Has(h) {
 			if _, ok := c.editors[h]; !ok {
-				e := newHeaderEditor(h, c.header, aerc.SelectedAccount().UiConfig())
+				e := newHeaderEditor(h, c.header, uiConfig)
 				if aerc.conf.Ui.CompletionPopovers {
-					e.input.TabComplete(cmpl.ForHeader(h), aerc.SelectedAccount().UiConfig().CompletionDelay)
+					e.input.TabComplete(cmpl.ForHeader(h), uiConfig.CompletionDelay)
 				}
 				c.editors[h] = e
 				c.focusable = append(c.focusable, e)
@@ -741,11 +741,10 @@ func (c *Composer) AddEditor(header string, value string, appendHeader bool) {
 		e.storeValue() // flush modifications from the user to the header
 		editor = e
 	} else {
-		e := newHeaderEditor(header, c.header,
-			c.aerc.SelectedAccount().UiConfig())
-		if c.config.Ui.CompletionPopovers {
-			e.input.TabComplete(c.completer.ForHeader(header),
-				c.config.Ui.CompletionDelay)
+		uiConfig := c.aerc.SelectedAccountUiConfig()
+		e := newHeaderEditor(header, c.header, uiConfig)
+		if uiConfig.CompletionPopovers {
+			e.input.TabComplete(c.completer.ForHeader(header), uiConfig.CompletionDelay)
 		}
 		c.editors[header] = e
 		c.layout = append(c.layout, []string{header})
diff --git a/widgets/msglist.go b/widgets/msglist.go
index 50ce24ee..ae0d2118 100644
--- a/widgets/msglist.go
+++ b/widgets/msglist.go
@@ -53,11 +53,13 @@ func (ml *MessageList) Invalidate() {
 
 func (ml *MessageList) Draw(ctx *ui.Context) {
 	ml.height = ctx.Height()
+	uiConfig := ml.aerc.SelectedAccountUiConfig()
 	ctx.Fill(0, 0, ctx.Width(), ctx.Height(), ' ',
-		ml.aerc.SelectedAccount().UiConfig().GetStyle(config.STYLE_MSGLIST_DEFAULT))
+		uiConfig.GetStyle(config.STYLE_MSGLIST_DEFAULT))
 
+	acct := ml.aerc.SelectedAccount()
 	store := ml.Store()
-	if store == nil {
+	if store == nil || acct == nil {
 		if ml.isInitalizing {
 			ml.spinner.Draw(ctx)
 			return
@@ -89,7 +91,7 @@ func (ml *MessageList) Draw(ctx *ui.Context) {
 		row          int = 0
 	)
 
-	if ml.aerc.SelectedAccount().UiConfig().ThreadingEnabled || store.BuildThreads() {
+	if uiConfig.ThreadingEnabled || store.BuildThreads() {
 		threads := store.Threads
 		counter := len(store.Uids())
 
@@ -119,8 +121,8 @@ func (ml *MessageList) Draw(ctx *ui.Context) {
 					}
 				}
 				fmtCtx := format.Ctx{
-					FromAddress:       ml.aerc.SelectedAccount().acct.From,
-					AccountName:       ml.aerc.SelectedAccount().Name(),
+					FromAddress:       acct.acct.From,
+					AccountName:       acct.Name(),
 					MsgInfo:           msg,
 					MsgNum:            row,
 					MsgIsMarked:       store.IsMarked(t.Uid),
@@ -144,8 +146,8 @@ func (ml *MessageList) Draw(ctx *ui.Context) {
 			uid := uids[i]
 			msg := store.Messages[uid]
 			fmtCtx := format.Ctx{
-				FromAddress: ml.aerc.SelectedAccount().acct.From,
-				AccountName: ml.aerc.SelectedAccount().Name(),
+				FromAddress: acct.acct.From,
+				AccountName: acct.Name(),
 				MsgInfo:     msg,
 				MsgNum:      row,
 				MsgIsMarked: store.IsMarked(uid),
@@ -183,8 +185,9 @@ func (ml *MessageList) Draw(ctx *ui.Context) {
 func (ml *MessageList) drawRow(textWidth int, ctx *ui.Context, uid uint32, row int, needsHeaders *[]uint32, fmtCtx format.Ctx) bool {
 	store := ml.store
 	msg := store.Messages[uid]
+	acct := ml.aerc.SelectedAccount()
 
-	if row >= ctx.Height() {
+	if row >= ctx.Height() || acct == nil {
 		return true
 	}
 
@@ -195,8 +198,8 @@ func (ml *MessageList) drawRow(textWidth int, ctx *ui.Context, uid uint32, row i
 	}
 
 	confParams := map[config.ContextType]string{
-		config.UI_CONTEXT_ACCOUNT: ml.aerc.SelectedAccount().AccountConfig().Name,
-		config.UI_CONTEXT_FOLDER:  ml.aerc.SelectedAccount().Directories().Selected(),
+		config.UI_CONTEXT_ACCOUNT: acct.AccountConfig().Name,
+		config.UI_CONTEXT_FOLDER:  acct.Directories().Selected(),
 	}
 	if msg.Envelope != nil {
 		confParams[config.UI_CONTEXT_SUBJECT] = msg.Envelope.Subject
@@ -288,7 +291,7 @@ func (ml *MessageList) MouseEvent(localX int, localY int, event tcell.Event) {
 			if ok {
 				ml.Select(selectedMsg)
 				acct := ml.aerc.SelectedAccount()
-				if acct.Messages().Empty() {
+				if acct == nil || acct.Messages().Empty() {
 					return
 				}
 				store := acct.Messages().Store()
@@ -433,7 +436,7 @@ func (ml *MessageList) ensureScroll() {
 }
 
 func (ml *MessageList) drawEmptyMessage(ctx *ui.Context) {
-	uiConfig := ml.aerc.SelectedAccount().UiConfig()
+	uiConfig := ml.aerc.SelectedAccountUiConfig()
 	msg := uiConfig.EmptyMessage
 	ctx.Printf((ctx.Width()/2)-(len(msg)/2), 0,
 		uiConfig.GetStyle(config.STYLE_MSGLIST_DEFAULT), "%s", msg)