fix: do not fail on empty input with --fail

alecthomas · claude · alecthomas · commit f19cf58c0a92 · 2026-07-08T12:06:37.000+10:00
io.ReadFull returns plain io.EOF when zero bytes are read, which
the guard treated as fatal, so 0-byte files or stdin printed
"chroma: EOF" and exited 1 — breaking the .lessfilter use case.

Co-Authored-By: Claude Fable 5 &lt;noreply@anthropic.com&gt;
diff --git a/cmd/chroma/main.go b/cmd/chroma/main.go
@@ -110,7 +110,7 @@ func prepareLenient(r io.Reader, filename string) (string, chroma.Lexer, error)
 func prepareSpecific(ctx *kong.Context, r io.Reader, filename string, peekSize, fullSize int) (string, chroma.Lexer) {
 	data := make([]byte, peekSize)
 	n, err := io.ReadFull(r, data)
-	if err != nil && !errors.Is(err, io.ErrUnexpectedEOF) {
+	if err != nil && !errors.Is(err, io.ErrUnexpectedEOF) && !errors.Is(err, io.EOF) {
 		ctx.FatalIfErrorf(err)
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -110,7 +110,7 @@ func prepareLenient(r io.Reader, filename string) (string, chroma.Lexer, error)`
`110`	`110`	`func prepareSpecific(ctx *kong.Context, r io.Reader, filename string, peekSize, fullSize int) (string, chroma.Lexer) {`
`111`	`111`	`data := make([]byte, peekSize)`
`112`	`112`	`n, err := io.ReadFull(r, data)`
`113`		`- if err != nil && !errors.Is(err, io.ErrUnexpectedEOF) {`
	`113`	`+ if err != nil && !errors.Is(err, io.ErrUnexpectedEOF) && !errors.Is(err, io.EOF) {`
`114`	`114`	`ctx.FatalIfErrorf(err)`
`115`	`115`	`}`
`116`	`116`