can1357/oh-my-pi · error · SyntaxError

Expected value after ':'

Error message

Expected value after ':'

What it means

Thrown by RelaxedJson.#object in strict mode when a ':' was consumed but end-of-input is reached before any value follows. The key/value pair cannot be completed, so strict mode refuses the input; partial mode would return the object parsed so far.

Source

Thrown at packages/utils/src/json-parse.ts:283

			}
			if (c === ",") {
				// Tolerate leading / doubled / trailing commas.
				this.#i++;
				continue;
			}
			const key = this.#key();
			this.#ws();
			if (this.#i < this.#n && this.#s[this.#i] === ":") {
				this.#i++;
			} else if (this.#partial) {
				return out;
			} else {
				throw new SyntaxError("Expected ':' in object");
			}
			this.#ws();
			if (this.#i >= this.#n) {
				if (this.#partial) return out;
				throw new SyntaxError("Expected value after ':'");
			}
			const value = this.#value(true);
			if (value === INCOMPLETE) return out;
			out[key] = value;
			this.#ws();
			const d = this.#i < this.#n ? this.#s[this.#i] : "";
			if (d === ",") {
				this.#i++;
				continue;
			}
			if (d === "}") {
				this.#i++;
				return out;
			}
			if (this.#partial) return out;
			throw new SyntaxError("Expected ',' or '}' in object");
		}
	}

View on GitHub (pinned to 9690622007)

Solutions

1. Ensure the full payload is read before parsing (await the stream/file completion)
2. Use parseStreamingJson for genuinely incomplete input — it auto-closes and returns the partial object
3. Use classifyJsonPrefix to know the buffer is still a 'prefix' and wait for more deltas before final parsing

Example fix

// before
const v = parseJsonWithRepair(`{"a":`); // SyntaxError: Expected value after ':'
// after
const v = parseStreamingJson(`{"a":`); // {} (partial-safe)

import { classifyJsonPrefix } from "@oh-my-pi/pi-utils/json-parse";
if (classifyJsonPrefix(text) !== "complete") {
  // input still incomplete (e.g. ends after ':') — do not final-parse yet
}

try {
  const value = parseJsonWithRepair<T>(text);
} catch (err) {
  if (err instanceof SyntaxError && err.message === "Expected value after ':'") {
    const partial = parseStreamingJson<T>(text); // returns object parsed so far
  } else throw err;
}

When it happens

Trigger: parseJsonWithRepair with input ending right after a colon: '{"a":' or '{"a": '. Occurs whenever a truncated payload happens to cut exactly between the colon and the value.

Common situations: LLM tool-call argument stream truncated mid-pair; a fixed-size read that cut the payload; log capture that clipped the buffer.

Related errors

• Unterminated object
• Expected ':' in object
• Expected ',' or '}' in object
• Unterminated array
• Unterminated string

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/ea14f0f19de21983. Report an issue: GitHub.