Remove unused functions such as `print` and use `error` function

Remove unused functions such as `print` and use `error` function

```
function print(text) {
outputElm.innerHTML = text.replace(/\n/g, '
');
}

function error(e) {
console.log(e);
errorElm.style.display = 'block';
errorElm.textContent = e.message;
}
```

Search the JavaScript source for the `print` and `error` function definitions and their callers, then inspect how query output and errors are displayed. Remove unused functions such as `print`, use `error` where appropriate, and verify that SQL execution still reports output and errors correctly in the browser.

Written by the indexing model from the issue text.