Add test cases verifying that invalid trailing comma syntaxes in list literals
(e.g. `[,]`, `[1,,]`, `[1,,2]`) and map literals (e.g. `{,}`, `{1:1,,}`, `{1:1,,2:2}`)
correctly produce compile errors when evaluated via Meta.eval in a Fiber.
Add a check in the map parsing function to break when encountering a closing brace after a comma, enabling trailing commas in map literals. Include a test case verifying that maps with trailing commas parse and execute correctly.