Catch errors from any participants.

[angelozerr]

All participants like diagnostics, completions, etc loop for each participant and if one of participant throws an error, it breaks the other participants. For diagnostics case it seems that when a participant throw an error, the LSP publishDiagnostics is not traced in the console.

We should try catch each participant and log the error for each participant which throw an error.

For instance I suspect in #945 that there is this problem.

XMLDiagnostics should look like this:

class XMLDiagnostics {

	private static final Logger LOGGER = Logger.getLogger(XMLDiagnostics.class.getName());

	private final XMLExtensionsRegistry extensionsRegistry;

	public XMLDiagnostics(XMLExtensionsRegistry extensionsRegistry) {
		this.extensionsRegistry = extensionsRegistry;
	}

	public List<Diagnostic> doDiagnostics(DOMDocument xmlDocument, XMLValidationSettings validationSettings,
			CancelChecker cancelChecker) {
		List<Diagnostic> diagnostics = new ArrayList<Diagnostic>();
		if (validationSettings == null || validationSettings.isEnabled()) {
			doExtensionsDiagnostics(xmlDocument, diagnostics, validationSettings, cancelChecker);
		}
		return diagnostics;
	}

	private void doExtensionsDiagnostics(DOMDocument xmlDocument, List<Diagnostic> diagnostics,
			XMLValidationSettings validationSettings, CancelChecker monitor) {
		for (IDiagnosticsParticipant diagnosticsParticipant : extensionsRegistry.getDiagnosticsParticipants()) {
			monitor.checkCanceled();
			try {
				diagnosticsParticipant.doDiagnostics(xmlDocument, diagnostics, validationSettings, monitor);
			} catch (CancellationException e) {
				throw e;
			} catch (Exception e) {
				LOGGER.log(Level.SEVERE, "Error while processing diagnostics for the participant '"
						+ diagnosticsParticipant.getClass().getName() + "'.", e);
			}
		}
	}
}

It should be fine to:

• do the same things for all participants.
• write tests with a participant which throw an error.