What causes "Invalid query: empty [] in ${query}" in can1357/oh-my-pi?

Put an explicit key or numeric index inside the brackets: '.foo[0]' or '.foo["key"]'.

Invalid query: empty [] in ${query}

Error message

Invalid query: empty [] in ${query}

What it means

parseQuery throws this when a bracket segment contains nothing (or only whitespace) between '[' and ']'. Bracket notation must carry either a numeric index, a quoted key, or a bare token; '[]' and '[ ]' are rejected as meaningless.

Source

Thrown at packages/coding-agent/src/internal-urls/json-query.ts:39

	const tokens: Array<string | number> = [];
	let i = 0;

	const isIdentChar = (ch: string) => /[A-Za-z0-9_-]/.test(ch);

	while (i < input.length) {
		const ch = input[i];
		if (ch === ".") {
			i++;
			continue;
		}
		if (ch === "[") {
			const closeIndex = input.indexOf("]", i + 1);
			if (closeIndex === -1) {
				throw new Error(`Invalid query: missing ] in ${query}`);
			}
			const raw = input.slice(i + 1, closeIndex).trim();
			if (!raw) {
				throw new Error(`Invalid query: empty [] in ${query}`);
			}
			const quote = raw[0];
			if ((quote === '"' || quote === "'") && raw.endsWith(quote)) {
				let inner = raw.slice(1, -1);
				inner = inner.replace(/\\(["'\\])/g, "$1");
				tokens.push(inner);
			} else if (/^\d+$/.test(raw)) {
				tokens.push(Number(raw));
			} else {
				tokens.push(raw);
			}
			i = closeIndex + 1;
			continue;
		}

		const start = i;
		while (i < input.length && isIdentChar(input[i])) {
			i++;

View on GitHub (pinned to 9690622007)

Solutions

Put an explicit key or numeric index inside the brackets: '.foo[0]' or '.foo["key"]'.
If you intended jq-style array iteration, implement a loop over the array in code instead — applyQuery only selects single elements.
Guard dynamic construction: skip empty segments before appending brackets.

Example fix

// before
const q = `.items[${idx}]`; // idx === ''
// after
const q = idx !== '' ? `.items[${idx}]` : `.items`;

Defensive patterns

Strategy: validation

Validate before calling

if (/\[\s*\]/.test(query)) throw new Error(`Empty [] in query: ${query}`);

Try / catch

try { tokens = parseQuery(query); } catch (e) { if (String(e.message).includes('empty []')) { /* skip segment or prompt for an index */ } else throw e; }

Prevention

Never use jq's '[]' iteration syntax — this parser selects single elements only.
Check that interpolated index/key variables are non-empty before building the query.
Prefer explicit indices from array length checks (idx < arr.length).

When it happens

Trigger: Calling parseQuery/applyQuery with '.foo[]', '.a[ ]', or consecutive brackets like '.foo[][0]'. Also produced by pathToQuery if a path segment somehow collapses to empty after filtering — though normally pathToQuery skips empty segments.

Common situations: Dynamically built queries where a segment variable was empty ('.' + name + '[]' with name=''); template strings whose interpolation produced nothing; users copying jq's '[]' iterate-all syntax which this mini-parser does not support.

Related errors

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/3e9ebeedd451d814. Report an issue: GitHub.