Move error handling code into its own library

go.mod

@@ -13,6 +13,7 @@ require (
 	github.com/google/uuid v1.6.0
 	github.com/kovidgoyal/dbus v0.0.0-20250519011319-e811c41c0bc1
 	github.com/kovidgoyal/exiffix v0.0.0-20250919160812-dbef770c2032
+	github.com/kovidgoyal/go-parallel v1.0.1
 	github.com/kovidgoyal/imaging v1.7.1
 	github.com/seancfoley/ipaddress-go v1.7.1
 	github.com/shirou/gopsutil/v3 v3.24.5

go.sum

@@ -28,6 +28,8 @@ github.com/kovidgoyal/dbus v0.0.0-20250519011319-e811c41c0bc1 h1:rMY/hWfcVzBm6BL
 github.com/kovidgoyal/dbus v0.0.0-20250519011319-e811c41c0bc1/go.mod h1:RbNG3Q1g6GUy1/WzWVx+S24m7VKyvl57vV+cr2hpt50=
 github.com/kovidgoyal/exiffix v0.0.0-20250919160812-dbef770c2032 h1:TEV9lpo2a6fP1byiDsoJe2fXpvrj2itae41xMM+bEAg=
 github.com/kovidgoyal/exiffix v0.0.0-20250919160812-dbef770c2032/go.mod h1:VU38Nlbvb0lbyS5YkopCZMS5HuJ5QLVJBxRWyzq79q4=
+github.com/kovidgoyal/go-parallel v1.0.1 h1:nYUjN+EdpbmQjTg3N5eTUInuXTB3/1oD2vHdaMfuHoI=
+github.com/kovidgoyal/go-parallel v1.0.1/go.mod h1:BJNIbe6+hxyFWv7n6oEDPj3PA5qSw5OCtf0hcVxWJiw=
 github.com/kovidgoyal/imaging v1.7.1 h1:wQJf0LdE06kIlSFIFFBKJp9N4D0CJmNMfWuog+YQka4=
 github.com/kovidgoyal/imaging v1.7.1/go.mod h1:i0dBmu7j5/g4QhvS79Cx9IoiK7P02z1SwBJFDazrGLE=
 github.com/lufia/plan9stats v0.0.0-20230326075908-cb1d2100619a h1:N9zuLhTvBSRt0gWSiJswwQ2HqDmtX/ZCDJURnKUt1Ik=

kittens/choose_files/image_preview.go

@@ -10,6 +10,7 @@ import (
 	"sync"
 	"sync/atomic"
 
+	"github.com/kovidgoyal/go-parallel"
 	"github.com/kovidgoyal/kitty/tools/disk_cache"
 	"github.com/kovidgoyal/kitty/tools/icons"
 	"github.com/kovidgoyal/kitty/tools/utils"
@@ -114,8 +115,7 @@ func (p *ImagePreview) ensure_source_image() (err error) {
 func (p *ImagePreview) render_image(h *Handler, x, y, width, height int) {
 	defer func() {
 		if r := recover(); r != nil {
-			text, _ := utils.Format_stacktrace_on_panic(r)
+			h.err_chan <- parallel.Format_stacktrace_on_panic(r, 1)
-			h.err_chan <- fmt.Errorf("%s", text)
 			p.WakeupMainThread()
 		}
 	}()
@@ -160,8 +160,7 @@ func (p *ImagePreview) Render(h *Handler, x, y, width, height int) {
 func (p *ImagePreview) start_rendering() {
 	defer func() {
 		if r := recover(); r != nil {
-			text, _ := utils.Format_stacktrace_on_panic(r)
+			p.render_channel <- render_data{err: parallel.Format_stacktrace_on_panic(r, 1)}
-			p.render_channel <- render_data{err: fmt.Errorf("%s", text)}
 		}
 		close(p.render_channel)
 		p.WakeupMainThread()

kittens/choose_files/preview.go

@@ -11,6 +11,7 @@ import (
 	"sync"
 	"unicode/utf8"
 
+	"github.com/kovidgoyal/go-parallel"
 	"github.com/kovidgoyal/kitty/tools/highlight"
 	"github.com/kovidgoyal/kitty/tools/icons"
 	"github.com/kovidgoyal/kitty/tools/tui/loop"
@@ -261,8 +262,8 @@ func (pm *PreviewManager) highlight_file_async(path string, output chan highligh
 	go func() {
 		defer func() {
 			if r := recover(); r != nil {
-				text, _ := utils.Format_stacktrace_on_panic(r)
+				err := parallel.Format_stacktrace_on_panic(r, 1)
-				debugprintln(fmt.Sprintf("Failed to highlight: %s with panic: %s", path, text))
+				debugprintln(fmt.Sprintf("Failed to highlight: %s with panic: %s", path, err))
 			}
 			close(output)
 			pm.WakeupMainThread()

kittens/choose_files/save-file.go

@@ -6,6 +6,7 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/kovidgoyal/go-parallel"
 	"github.com/kovidgoyal/kitty/tools/cli"
 	"github.com/kovidgoyal/kitty/tools/tui/loop"
 	"github.com/kovidgoyal/kitty/tools/utils"
@@ -26,8 +27,7 @@ func FilePromptCompleter(getcwd func() string) func(string, string) *cli.Complet
 	return func(before_cursor, after_cursor string) (ans *cli.Completions) {
 		defer func() {
 			if r := recover(); r != nil {
-				text, err := utils.Format_stacktrace_on_panic(r)
+				err := parallel.Format_stacktrace_on_panic(r, 1)
-				debugprintln(text)
 				debugprintln(err)
 			}
 		}()

kittens/choose_files/scan.go

@@ -18,6 +18,7 @@ import (
 	"unicode"
 	"unicode/utf8"
 
+	"github.com/kovidgoyal/go-parallel"
 	"github.com/kovidgoyal/kitty/tools/fzf"
 	"github.com/kovidgoyal/kitty/tools/ignorefiles"
 	"github.com/kovidgoyal/kitty/tools/utils"
@@ -219,8 +220,8 @@ func (fss *FileSystemScanner) worker() {
 		defer fss.unlock()
 		fss.in_progress.Store(false)
 		if r := recover(); r != nil {
-			st, qerr := utils.Format_stacktrace_on_panic(r)
+			qerr := parallel.Format_stacktrace_on_panic(r, 1)
-			fss.err = fmt.Errorf("%w\n%s", qerr, st)
+			fss.err = qerr
 		}
 		for _, l := range fss.listeners {
 			close(l)
@@ -532,8 +533,8 @@ func (fss *FileSystemScorer) worker(on_results chan bool, worker_wait *sync.Wait
 		defer worker_wait.Done()
 		if r := recover(); r != nil {
 			if fss.keep_going.Load() {
-				st, qerr := utils.Format_stacktrace_on_panic(r)
+				qerr := parallel.Format_stacktrace_on_panic(r, 1)
-				fss.on_results(fmt.Errorf("%w\n%s", qerr, st), true)
+				fss.on_results(qerr, true)
 			}
 		} else {
 			if fss.keep_going.Load() {

tools/fzf/algo.go

@@ -8,7 +8,7 @@ import (
 	"unicode"
 	"unicode/utf8"
 
-	"github.com/kovidgoyal/kitty/tools/utils"
+	"github.com/kovidgoyal/go-parallel"
 	"golang.org/x/text/unicode/norm"
 )
 
@@ -362,12 +362,11 @@ func (m *FuzzyMatcher) score(items []string, pattern string, scoring_func func(s
 	pat := []rune(pattern)
 	pattern_is_ascii := !slices.ContainsFunc(pat, func(r rune) bool { return r >= utf8.RuneSelf })
 	ans = make([]Result, len(items))
-	err = utils.Run_in_parallel_over_range(0, func(start, end int) error {
+	err = parallel.Run_in_parallel_over_range(0, func(start, end int) {
 		s := slab{}
 		for i := start; i < end; i++ {
 			ans[i] = scoring_func(items[i], pat, pattern_is_ascii, &s, as_chars)
 		}
-		return nil
 	}, 0, len(items))
 	return
 

tools/highlight/impl.go

@@ -10,6 +10,7 @@ import (
 	"github.com/alecthomas/chroma/v2"
 	"github.com/alecthomas/chroma/v2/lexers"
 	"github.com/alecthomas/chroma/v2/styles"
+	"github.com/kovidgoyal/go-parallel"
 	"github.com/kovidgoyal/kitty/tools/utils"
 )
 
@@ -185,8 +186,7 @@ func (h *highlighter) Sanitize(x string) string { return h.sanitize(x) }
 func (h *highlighter) HighlightFile(path string, srd StyleResolveData) (highlighted_string string, err error) {
 	defer func() {
 		if r := recover(); r != nil {
-			text, _ := utils.Format_stacktrace_on_panic(r)
+			err = parallel.Format_stacktrace_on_panic(r, 1)
-			err = fmt.Errorf("%s", text)
 		}
 	}()
 	filename_for_detection := filepath.Base(path)

tools/tui/loop/api.go

@@ -12,6 +12,7 @@ import (
 
 	"golang.org/x/sys/unix"
 
+	"github.com/kovidgoyal/go-parallel"
 	"github.com/kovidgoyal/kitty/tools/tty"
 	"github.com/kovidgoyal/kitty/tools/utils"
 	"github.com/kovidgoyal/kitty/tools/utils/style"
@@ -324,18 +325,17 @@ func (self *Loop) DebugPrintln(args ...any) {
 func (self *Loop) Run() (err error) {
 	defer func() {
 		if r := recover(); r != nil {
-			var text string
+			err = parallel.Format_stacktrace_on_panic(r, 1)
-			text, err = utils.Format_stacktrace_on_panic(r)
 			is_terminal := tty.IsTerminal(os.Stderr.Fd())
 			if is_terminal {
 				os.Stderr.WriteString("\x1b]\x1b\\\x1bc\x1b[H\x1b[2J") // reset terminal
 			}
-			os.Stderr.WriteString(text)
+			os.Stderr.WriteString(err.Error())
 			os.Stderr.WriteString("\n")
 			if is_terminal {
 				if term, err := tty.OpenControllingTerm(tty.SetRaw); err == nil {
 					defer term.RestoreAndClose()
-					term.DebugPrintln(text)
+					term.DebugPrintln(err.Error())
 					fmt.Println("Press any key to exit.\r")
 					buf := make([]byte, 16)
 					_, _ = term.Read(buf)
@@ -592,8 +592,7 @@ type SizedText struct {
 
 func (self *Loop) RecoverFromPanicInGoRoutine() {
 	if r := recover(); r != nil {
-		text, err := utils.Format_stacktrace_on_panic(r)
+		err := parallel.Format_stacktrace_on_panic(r, 1)
-		err = fmt.Errorf("Panicked in non-main go routine\n%s\n%w", text, err)
 		// print to kitty stdout as multiple go routines might panic but only
 		// one panic is reported by the main loop panic_channel
 		if f := tty.KittyStdout(); f != nil {

tools/tui/loop/read.go

@@ -12,6 +12,7 @@ import (
 
 	"golang.org/x/sys/unix"
 
+	"github.com/kovidgoyal/go-parallel"
 	"github.com/kovidgoyal/kitty/tools/tty"
 	"github.com/kovidgoyal/kitty/tools/utils"
 )
@@ -46,8 +47,8 @@ func read_ignoring_temporary_errors(f *tty.Term, buf []byte) (int, error) {
 func read_from_tty(pipe_r *os.File, term *tty.Term, results_channel chan<- []byte, err_channel chan<- error, quit_channel <-chan byte, leftover_channel chan<- []byte) {
 	defer func() {
 		if r := recover(); r != nil {
-			text, _ := utils.Format_stacktrace_on_panic(r)
+			err := parallel.Format_stacktrace_on_panic(r, 1)
-			err_channel <- fmt.Errorf("%s", text)
+			err_channel <- err
 		}
 	}()
 	keep_going := true
@@ -123,7 +124,7 @@ func read_until_primary_device_attributes_response(term *tty.Term, initial_bytes
 	go func() {
 		defer func() {
 			if r := recover(); r != nil {
-				text, _ := utils.Format_stacktrace_on_panic(r)
+				text := parallel.Format_stacktrace_on_panic(r, 1).Error()
 				received <- fmt.Errorf("%s", text)
 			}
 		}()

tools/tui/loop/write.go

@@ -10,6 +10,7 @@ import (
 
 	"golang.org/x/sys/unix"
 
+	"github.com/kovidgoyal/go-parallel"
 	"github.com/kovidgoyal/kitty/tools/tty"
 	"github.com/kovidgoyal/kitty/tools/utils"
 )
@@ -170,8 +171,7 @@ func write_to_tty(
 ) {
 	defer func() {
 		if r := recover(); r != nil {
-			text, _ := utils.Format_stacktrace_on_panic(r)
+			err_channel <- parallel.Format_stacktrace_on_panic(r, 1)
-			err_channel <- fmt.Errorf("%s", text)
 		}
 	}()
 	keep_going := true

tools/tui/subseq/score.go

@@ -7,6 +7,7 @@ import (
 	"slices"
 	"strings"
 
+	"github.com/kovidgoyal/go-parallel"
 	"github.com/kovidgoyal/kitty/tools/utils"
 )
 
@@ -215,12 +216,11 @@ func ScoreItems(query string, items []string, opts Options) []*Match {
 	ropts := resolved_options_type{
 		level1: []rune(opts.Level1), level2: []rune(opts.Level2), level3: []rune(opts.Level3),
 	}
-	utils.Run_in_parallel_over_range(opts.NumberOfThreads, func(start, limit int) error {
+	parallel.Run_in_parallel_over_range(opts.NumberOfThreads, func(start, limit int) {
 		w := workspace_type{}
 		for i := start; i < limit; i++ {
 			ans[i] = score_item(items[i], i, nr, &ropts, &w)
 		}
-		return nil
 	}, 0, len(items))
 	return ans
 }

tools/utils/images/utils.go

@@ -8,7 +8,7 @@ import (
 	"sync"
 	"sync/atomic"
 
-	"github.com/kovidgoyal/kitty/tools/utils"
+	"github.com/kovidgoyal/go-parallel"
 )
 
 var _ = fmt.Print
@@ -55,8 +55,7 @@ func (self *Context) SafeParallel(start, stop int, fn func(<-chan int)) (err err
 		go func() {
 			defer func() {
 				if r := recover(); r != nil {
-					text, _ := utils.Format_stacktrace_on_panic(r)
+					err = parallel.Format_stacktrace_on_panic(r, 1)
-					err = fmt.Errorf("%s", text)
 				}
 				wg.Done()
 			}()

tools/utils/misc.go

@@ -68,80 +68,6 @@ func Filter[T any](s []T, f func(x T) bool) []T {
 	return ans
 }
 
-func Format_stacktrace_on_panic(r any) (text string, err error) {
-	pcs := make([]uintptr, 512)
-	n := runtime.Callers(3, pcs)
-	lines := []string{}
-	frames := runtime.CallersFrames(pcs[:n])
-	rt := fmt.Sprint(r)
-	if strings.HasPrefix(rt, "Panicked with error:") {
-		err = fmt.Errorf("%s", rt)
-		lines = append(lines, "Panic caused by previous panic (probably in a gouroutine). Previous panic:\r\n")
-		lines = append(lines, rt)
-		lines = append(lines, "\r\n\r\nStacktrace of current panic (most recent call first):\r\n")
-	} else {
-		err = fmt.Errorf("Panicked: %s", r)
-		lines = append(lines, fmt.Sprintf("\r\nPanicked with error: %s\r\nStacktrace (most recent call first):\r\n", r))
-	}
-	found_first_frame := false
-	for frame, more := frames.Next(); more; frame, more = frames.Next() {
-		if !found_first_frame {
-			if strings.HasPrefix(frame.Function, "runtime.") {
-				continue
-			}
-			found_first_frame = true
-		}
-		lines = append(lines, fmt.Sprintf("%s\r\n\t%s:%d\r\n", frame.Function, frame.File, frame.Line))
-	}
-	text = strings.Join(lines, "")
-	return strings.TrimSpace(text), err
-}
-
-// Run the specified function in parallel over chunks from the specified range.
-// If the function panics, it is turned into a regular error.
-func Run_in_parallel_over_range(num_procs int, f func(int, int) error, start, limit int) (err error) {
-	num_items := limit - start
-	if num_procs <= 0 {
-		num_procs = runtime.NumCPU()
-	}
-	num_procs = max(1, min(num_procs, num_items))
-	if num_procs < 2 {
-		defer func() {
-			if r := recover(); r != nil {
-				stacktrace, e := Format_stacktrace_on_panic(r)
-				err = fmt.Errorf("%s\n\n%w", stacktrace, e)
-			}
-		}()
-		return f(start, limit)
-	}
-	chunk_sz := max(1, num_items/num_procs)
-	var wg sync.WaitGroup
-	echan := make(chan error, num_procs)
-	for start < limit {
-		end := min(start+chunk_sz, limit)
-		wg.Add(1)
-		go func(start, end int) {
-			defer func() {
-				if r := recover(); r != nil {
-					stacktrace, e := Format_stacktrace_on_panic(r)
-					echan <- fmt.Errorf("%s\n\n%w", stacktrace, e)
-				}
-				wg.Done()
-			}()
-			if err := f(start, end); err != nil {
-				echan <- err
-			}
-		}(start, end)
-		start = end
-	}
-	wg.Wait()
-	close(echan)
-	for qerr := range echan {
-		return qerr
-	}
-	return
-
-}
 func Map[T any, O any](f func(x T) O, s []T) []O {
 	ans := make([]O, 0, len(s))
 	for _, x := range s {