LilyPondTool provides quick parse of the score without running LilyPond. This feature is used by the Structure Browser (provided by the SideKick plugin), but will also let you find simple errors faster, and helps in the automatic code completion.
Parsing is done when you save the document, or you can set it to happen on every keystroke in >>SideKick
You may find the Navigator plugin useful, because it lets you navigate back and forth through the places where you edited the score.
If you dock the Structure Browser, you can use it to easily jump to the parts of the score.
If you save the document, the parser looks for errors in the syntax, including:
Unmatched braces
Unmatched brackets and parentheses
Undeclared variables
and a lot more...
This integrated parser almost fully compatible with the real LilyPond syntax, so using this you will catch most errors that would make LilyPond to complain about. (Due to current limitations some times false alarms can happen.)
Errors that are found when saving the documents and errors that are found during processing the score with LilyPond are put in the error list provided by the ErrorList plugin. You can set the ErrorList plugin to appear when there are errors. Perhaps you would like to dock it.
You can see the erroneous places underlined, and you can easily get to them with a click in the Error List.
When you press the | key (that puts a bar check in the score, so LilyPond will report if there would be no barline there), the length of the last measure is counted and displayed in the status bar. For example, with the input
c8 d e4 f |
a small tooltip will show "3/4", and the status bar will show: 'Beat: 3/4'