Objects have more structure to get wrong than arrays - a key must be a string, a colon must separate key from value, and members are comma-separated. Today you report each of those object failures at its exact position.
Report a non-string key, a missing colon, and a missing comma in an object, each with a position.
An object member has three required parts in order - a string key, a colon,
and a value - and members are joined by commas. Each of those points is a place
the input can be wrong, and a good parser names which one. A non-string key like the
1 in {1:2} is expected string key. A key with no colon after it, as in
{"a" 1}, is expected colon after key, pointing at the token that showed up
instead of the colon. And a member not followed by a comma or a closing brace, like
the second string in {"a":1 "b":2}, is expected comma or closing brace.
The trailing-comma rule from arrays applies here too, but with the object’s own
wording: after a comma the parser expects the next member’s key, so {"a":1,}
reports expected string key at the closing brace. Each check reads the current
token, and when it is not what the grammar demands, produces a ParseError carrying
that token’s position. Together they turn every structural slip in an object into a
precise, actionable message.
// in the object loop, at each step check the token and message:// key -> if not a String token: "expected string key"// colon -> if not ':' : "expected colon after key"// after a value -> expect ',' (continue) or '}' (stop),// else "expected comma or closing brace"// each message points at the offending token's position