cli: Handle invalid board paths

ci/release/changelogs/next.md

@@ -20,3 +20,4 @@
 - Correctly reports errors from invalid values set by globs. [#1691](https://github.com/terrastruct/d2/pull/1691)
 - Fixes panic when spread substitution referenced a nonexistant var. [#1695](https://github.com/terrastruct/d2/pull/1695)
 - Fixes incorrect appendix icon numbering. [#1704](https://github.com/terrastruct/d2/pull/1704)
+- Fixes crash when using `--watch` and navigating to an invalid board path [#1693](https://github.com/terrastruct/d2/pull/1693)

d2cli/fmt.go

@@ -17,7 +17,7 @@ import (
 func fmtCmd(ctx context.Context, ms *xmain.State) (err error) {
 	defer xdefer.Errorf(&err, "failed to fmt")
 
-	ms.Opts = xmain.NewOpts(ms.Env, ms.Log, ms.Opts.Flags.Args()[1:])
+	ms.Opts = xmain.NewOpts(ms.Env, ms.Opts.Flags.Args()[1:])
 	if len(ms.Opts.Args) == 0 {
 		return xmain.UsageErrorf("fmt must be passed at least one file to be formatted")
 	}

d2cli/main.go

@@ -2,6 +2,7 @@ package d2cli
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
@@ -490,6 +491,8 @@ func compile(ctx context.Context, ms *xmain.State, plugins []d2plugin.Plugin, la
 	default:
 		compileDur := time.Since(start)
 		if animateInterval <= 0 {
+			b, _ := json.MarshalIndent(diagram, "", "  ")
+			println("\033[1;31m--- DEBUG:", string(b), "\033[m")
 			// Rename all the "root.layers.x" to the paths that the boards get output to
 			linkToOutput, err := resolveLinks("root", outputPath, diagram)
 			if err != nil {
@@ -503,7 +506,7 @@ func compile(ctx context.Context, ms *xmain.State, plugins []d2plugin.Plugin, la
 
 		board := diagram.GetBoard(boardPath)
 		if board == nil {
-			return nil, false, fmt.Errorf("Diagram with path %s not found", boardPath)
+			return nil, false, fmt.Errorf(`Diagram with path "%s" not found. Did you mean to specify a board like "layers.%s"?`, boardPath, boardPath)
 		}
 
 		boards, err := render(ctx, ms, compileDur, plugin, renderOpts, inputPath, outputPath, bundle, forceAppendix, page, ruler, board)

d2plugin/plugin_dagre.go

@@ -61,7 +61,7 @@ func (p *dagrePlugin) HydrateOpts(opts []byte) error {
 func (p *dagrePlugin) Info(ctx context.Context) (*PluginInfo, error) {
 	p.mu.Lock()
 	defer p.mu.Unlock()
-	opts := xmain.NewOpts(nil, nil, nil)
+	opts := xmain.NewOpts(nil, nil)
 	flags, err := p.Flags(ctx)
 	if err != nil {
 		return nil, err

d2plugin/plugin_elk.go

@@ -76,7 +76,7 @@ func (p *elkPlugin) HydrateOpts(opts []byte) error {
 }
 
 func (p elkPlugin) Info(ctx context.Context) (*PluginInfo, error) {
-	opts := xmain.NewOpts(nil, nil, nil)
+	opts := xmain.NewOpts(nil, nil)
 	flags, err := p.Flags(ctx)
 	if err != nil {
 		return nil, err

e2etests-cli/main_test.go

@@ -3,12 +3,17 @@ package e2etests_cli
 import (
 	"bytes"
 	"context"
+	"fmt"
+	"net/http"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"testing"
 	"time"
 
+	"github.com/davecgh/go-spew/spew"
+	"nhooyr.io/websocket"
 	"oss.terrastruct.com/util-go/assert"
 	"oss.terrastruct.com/util-go/diff"
 	"oss.terrastruct.com/util-go/xmain"
@@ -544,6 +549,77 @@ i used to read
 				assert.Equal(t, "x -> y\n", string(gotBar))
 			},
 		},
+		{
+			name: "watch",
+			run: func(t *testing.T, ctx context.Context, dir string, env *xos.Env) {
+				writeFile(t, dir, "index.d2", `
+a -> b
+b.link: cream
+
+layers: {
+    cream: {
+        c -> b
+    }
+}`)
+				stderr := &bytes.Buffer{}
+				tms := testMain(dir, env, "--watch", "--browser=0", "index.d2")
+				tms.Stderr = stderr
+
+				doneChan := make(chan struct{}, 1)
+
+				tms.Start(t, ctx)
+				defer tms.Cleanup(t)
+
+				go tms.Wait(ctx)
+
+				ticker := time.NewTicker(100 * time.Millisecond)
+				urlRE := regexp.MustCompile(`127.0.0.1:([0-9]+)`)
+				compiled := false
+				go func() {
+					var url string
+					for i := 0; i < 10 && url == ""; i++ {
+						select {
+						case <-ticker.C:
+							out := string(stderr.Bytes())
+							url = urlRE.FindString(out)
+							compiled, _ = regexp.MatchString(`failed to recompile`, out)
+							println("\033[1;31m--- DEBUG:", compiled, "\033[m")
+						case <-ctx.Done():
+							ticker.Stop()
+							return
+						}
+					}
+
+					if url != "" {
+						c, _, err := websocket.Dial(ctx, fmt.Sprintf("ws://%s/watch", url), nil)
+						assert.Success(t, err)
+
+						req, err := http.NewRequestWithContext(ctx, "GET", fmt.Sprintf("http://%s/cream", url), nil)
+						assert.Success(t, err)
+						var httpClient = &http.Client{}
+						resp, err := httpClient.Do(req)
+						assert.Success(t, err)
+						defer resp.Body.Close()
+						assert.Equal(t, 200, resp.StatusCode)
+
+						time.Sleep(1000)
+						spew.Dump(string(stderr.Bytes()))
+
+						_, _, err = c.Read(ctx)
+						spew.Dump(err)
+
+						defer c.Close(websocket.StatusNormalClosure, "")
+					}
+
+					doneChan <- struct{}{}
+				}()
+
+				<-doneChan
+
+				err := tms.Signal(ctx, os.Interrupt)
+				assert.Error(t, err)
+			},
+		},
 	}
 
 	ctx := context.Background()