internal/debug: bug fix: do not panic when go-list fails

internal/debug/caller.go

@@ -15,8 +15,10 @@
 package debug
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
+	"os"
 	"os/exec"
 	"path"
 	"path/filepath"
@@ -41,13 +43,17 @@ const (
 // FirstCaller returns the file and line number of the first caller outside of Ebitengine.
 func FirstCaller() (file string, line int, callerType CallerType) {
 	ebitengineFileDirOnce.Do(func() {
+		var stderr bytes.Buffer
 		cmd := exec.Command("go", "list", "-f", "{{.Dir}}", "github.com/hajimehoshi/ebiten/v2")
+		cmd.Stderr = &stderr
 		out, err := cmd.Output()
 		if errors.Is(err, exec.ErrNotFound) {
 			return
 		}
 		if err != nil {
-			panic(fmt.Sprintf("debug: go list -f {{.Dir}} failed: %v", err))
+			fmt.Fprintf(os.Stderr, "debug: go list -f {{.Dir}} failed: %v\n", err)
+			fmt.Fprintf(os.Stderr, "%s\n", stderr.String())
+			return
 		}
 		ebitengineFileDir = filepath.ToSlash(strings.TrimSpace(string(out)))
 	})