Fixed regression from 3536438d

We were sending an empty string to the output channel when `ping`
messages were received from Anthropic's API. This was causing the TUI to
break since we started doing an empty chunk check (and mistakenly not
waiting for future chunks if one was received).

This commit makes it so we no longer an empty string on the ping message
from Anthropic, and we update the handling of msgAssistantChunk and
msgAssistantReply to make it less likely that we forget to wait for the
next chunk/reply.

pkg/lmcli/provider/anthropic/anthropic.go

@@ -229,8 +229,7 @@ func (c *AnthropicClient) CreateChatCompletionStream(
 			case "message_start":
 				// noop
 			case "ping":
-				// write an empty string to signal start of text
-				output <- ""
+				// signals start of text - currently ignoring
 			case "content_block_start":
 				// ignore?
 			case "content_block_delta":

pkg/tui/views/chat/chat.go

@@ -278,6 +278,8 @@ func (m Model) Update(msg tea.Msg) (Model, tea.Cmd) {
 		m.updateContent()
 		m.content.GotoBottom()
 	case msgResponseChunk:
+		cmds = append(cmds, m.waitForChunk()) // wait for the next chunk
+
 		chunk := string(msg)
 		if chunk == "" {
 			break
@@ -295,7 +297,6 @@ func (m Model) Update(msg tea.Msg) (Model, tea.Cmd) {
 			})
 		}
 		m.updateContent()
-		cmds = append(cmds, m.waitForChunk()) // wait for the next chunk
 
 		// show cursor and reset blink interval (simulate typing)
 		m.replyCursor.Blink = false
@@ -304,7 +305,8 @@ func (m Model) Update(msg tea.Msg) (Model, tea.Cmd) {
 		m.tokenCount++
 		m.elapsed = time.Now().Sub(m.startTime)
 	case msgAssistantReply:
-		// the last reply that was being worked on is finished
+		cmds = append(cmds, m.waitForReply()) // wait for the next reply
+
 		reply := models.Message(msg)
 		reply.Content = strings.TrimSpace(reply.Content)
 
@@ -332,7 +334,6 @@ func (m Model) Update(msg tea.Msg) (Model, tea.Cmd) {
 		}
 
 		m.updateContent()
-		cmds = append(cmds, m.waitForReply())
 	case msgResponseEnd:
 		m.waitingForReply = false
 		last := len(m.messages) - 1