JuliusBrussee/caveman · warning

cacheengine: unexpected delimiter

Error message

cacheengine: unexpected delimiter

What it means

Thrown by inspectUniqueJSONValue's default branch when the decoded token is a json.Delim that is neither '{' nor '[' — i.e. a leading '}' or ']'. Go's streaming decoder only returns delimiters at structurally valid positions, so this branch is a defensive unreachable guard against decoder/protocol changes, not a condition real input should produce.

Source

Thrown at cacheengine/native.go:531

		if root {
			return false, errors.New("cacheengine: request root must be object")
		}
		found := false
		path = append(path, "*")
		for decoder.More() {
			childFound, err := inspectUniqueJSONValue(decoder, false, depth+1, provider, path)
			if err != nil {
				return false, err
			}
			found = found || childFound
		}
		closing, err := decoder.Token()
		if err != nil || closing != json.Delim(']') {
			return false, errors.New("cacheengine: invalid array close")
		}
		return found, nil
	default:
		return false, errors.New("cacheengine: unexpected delimiter")
	}
}

View on GitHub (pinned to 27d5a3981a)

Solutions

1. If you ever see it, capture the exact body and library version and report it upstream — the input itself is not fixable client-side
2. Ensure you pass the standard *json.Decoder contract if you wrap the engine's inspection path
3. Keep the engine and codec versions in lockstep (no vendored forks of encoding/json)

// n/a

if err := eng.Execute(ctx, req); err != nil && strings.Contains(err.Error(), "unexpected delimiter") { captureBodyForReport(body); return err }

When it happens

Trigger: Effectively unreachable via encoding/json: a Token() call never yields a closing delimiter where an opening value is expected (that is a syntax error returned as err instead). It exists to fail loudly if decoder semantics ever change.

Common situations: None in practice; if observed, suspect a wrapped/patched decoder, a custom Token implementation, or a library version whose walker is out of sync with the codec.

Related errors

• cacheengine: segment exceeds framing limit
• cacheengine: JSON nesting limit exceeded
• cacheengine: request root must be object
• cacheengine: duplicate or invalid object key
• cacheengine: invalid object close

AI-assisted analysis of JuliusBrussee/caveman@27d5a3981a (2026-08-15). Data as JSON: /api/errors/9b17db1f2ac9be81. Report an issue: GitHub.