This is the method with the error detection logic that you need to implement:
767683
@Override
  public RuleMatch[] match(AnalyzedSentence sentence) throws IOException {
    List<RuleMatch> ruleMatches = new ArrayList<>();

    // Let's get all the tokens (i.e. words) of this sentence, but not the spaces:
    AnalyzedTokenReadings[] tokens = sentence.getTokensWithoutWhitespace();
    
    // No let's iterate over those - note that the first token will
    // be a special token that indicates the start of a sentence:
    for (AnalyzedTokenReadings token : tokens) {
      
      System.out.println("Token: " + token.getToken());  // the original word from the input text
      
      // A word can have more than one reading, e.g. 'dance' can be a verb or a noun,
      // so we iterate over the readings:
      for (AnalyzedToken analyzedToken : token.getReadings()) {
        System.out.println("  Lemma: " + analyzedToken.getLemma());
        System.out.println("  POS: " + analyzedToken.getPOSTag());
      }
      
      // You can add your own logic here to find errors. Here, we just consider
      // the word "demo" an error and create a rule match that LanguageTool will
      // then show to the user:
      if (token.getToken().equals("demo")) {
        RuleMatch ruleMatch = new RuleMatch(this, sentence, token.getStartPos(), token.getEndPos(), "The demo rule thinks this looks wrong");
        ruleMatch.setSuggestedReplacement("blablah");  // the user will see this as a suggested correction
        ruleMatches.add(ruleMatch);
      }
    }

    return toRuleMatchArray(ruleMatches);
  }
136068
static public function catchFatal()
    {
        $error = error_get_last();
        if ($error["type"] == E_ERROR 
            || $error['type'] == E_PARSE 
            || $error['type'] == E_CORE_ERROR
            || $error['type'] == E_COMPILE_ERROR) {
            self::errorHandler($error["type"], $error["message"], $error["file"], $error["line"]);
            /**
              Put fatals in the error log as well as the debug log
              For good measure, put them in STDERR too. Try to
              ensure somebody notices.
            */
            $msg = $error['message']
                . ' Line ' . $error['line']
                . ', File ' . $error['file'];
            self::$logger->error($msg);
            file_put_contents('php://stderr', $msg, FILE_APPEND);
        }
    }
1315469
def on_error(self, ex):
        
        if self._d:
            self._d.errback()
            self._d = None
1172019
function onceConnected( error, methods ) {

  if( !error ) {
    console.log( 'Connected to %s. There are %d methods available.', this.get( 'url' ), this.get( 'methods' ).length );
  }

  //console.log( require( 'util' ).inspect( this.get( 'methods' ), {showHidden: false, depth: 2, colors: true} ) );

  this.methodCall('wpp.systemCheck', [ 1, process.env.WORDPRESS_USERNAME, process.env.WORDPRESS_PASSWORD ], function( error, data ) {
    console.log( 'error', require( 'util' ).inspect( error, {showHidden: false, depth: 2, colors: true} ) );
    console.log( 'data', require( 'util' ).inspect( data, {showHidden: false, depth: 2, colors: true} ) );
  });

  if( error ) {
    console.error( error.message );
  }

}
738676
function detectCustomErrorMessage(key) {
            if (typeof properties[key] === 'object' && properties[key].errorMessage && properties[key].value) {
                return properties[key];
            }
            else  if (_.isArray(properties[key])) {
                return {
                    value: properties[key][0],
                    errorMessage: properties[key][1]
                };
            }
            else {
                return {
                    value: properties[key],
                    errorMessage: undefined
                };
            }
        }
852033
def errorRecorder(self, lineNumber, offset, text, check):
        
        code = text.split(" ")[0]
        lineOffset = self.report.line_offset

        self.warnings.append((lineOffset + lineNumber,
                              offset + 1, code, text))
588829
protected function HandleError()
    {
        static $bErrorsHandled = false;
        if (!$bErrorsHandled) {
            $bErrorsHandled = true;
            $oMessageManager = TCMSMessageManager::GetInstance();
            $oGlobal = TGlobal::instance();
            $aErrorFields = $this->GetErrorFields();
            $aReturnedParameter = $oGlobal->GetUserData();
            $aTrackedErrors = array();
            $sConsumerName = self::MSG_MANAGER_NAME;
            foreach ($aErrorFields as $sErrorField) {
                if (array_key_exists($sErrorField, $aReturnedParameter) && $aReturnedParameter[$sErrorField] > 0) {
                    if (!in_array($aReturnedParameter[$sErrorField], $aTrackedErrors)) {
                        TTools::WriteLogEntry('OGONE Alias Gateway: error from alias gateway call: '.$sErrorField.'-'.$aReturnedParameter[$sErrorField], 1, __FILE__, __LINE__);
                        $oMessageManager->AddMessage($sConsumerName, 'PAYMENT-HANDLER-OGONE-ALIAS-GATEWAY-ERROR-'.$sErrorField.'-'.$aReturnedParameter[$sErrorField]);
                        $aTrackedErrors[] = $aReturnedParameter[$sErrorField];
                    }
                }
            }
        }
    }
402333
private void checkForError(JsonNode resp) throws WePayException
	{
		JsonNode errorNode = resp.get("error");
		if (errorNode != null)
			throw new WePayException(errorNode.asText(), resp.path("error_description").asText(), resp.path("error_code").asInt());
	}
665282
public static void verifyMethodCondition(@Nullable ErrorCollector errorCollector, @Nullable ValueRecorder recorder, @Nullable String text, int line, int column,
      @Nullable Object message, Object target, String method, Object[] args, boolean safe, boolean explicit, int lastVariableNum) {
    MatcherCondition matcherCondition = MatcherCondition.parse(target, method, args, safe);
    if (matcherCondition != null) {
      matcherCondition.verify(errorCollector, getValues(recorder), text, line, column, messageToString(message));
      return;
    }

    if (recorder != null) {
      recorder.startRecordingValue(lastVariableNum);
    }
    Object result = safe ? GroovyRuntimeUtil.invokeMethodNullSafe(target, method, args) :
        GroovyRuntimeUtil.invokeMethod(target, method, args);

    if (!explicit && result == null && isVoidMethod(target, method, args)) return;

    if (!GroovyRuntimeUtil.isTruthy(result)) {
      List<Object> values = getValues(recorder);
      if (values != null) CollectionUtil.setLastElement(values, result);
      final ConditionNotSatisfiedError conditionNotSatisfiedError = new ConditionNotSatisfiedError(
          new Condition(values, text, TextPosition.create(line, column), messageToString(message), null, null));
      errorCollector.collectOrThrow(conditionNotSatisfiedError);
    }
  }
113497
function processError (error) {
    if (_cb.beforeReturnError) { _cb.beforeReturnError(error); }
    if (_cb.returnError) { _cb.returnError(error, response); }
    if (_cb.afterReturnError) { _cb.afterReturnError(error); }
  }
622387
def check_error(result):
    
    return (result.value != ReturnCode.SUCCESSFUL) and (result.value < ReturnCode.WARNING)
1146248
protected function findErrors()
    {
        $session = session();
        if (!$session->has('errors') || !$session->get('errors')->hasBag('default')) {
            return;
        }
        /** @var MessageBag $messageBag */
        $messageBag = session()->get('errors')->getBag('default');
        if (isset($messageBag->messages()[$this->name])) {
            foreach ($messageBag->messages()[$this->name] as $error) {
                $this->addError($error);
            }
        }
    }
1147555
final void addError( ParsedElement parsedElement, ResourceKey errorMsg )
  {
    verify( parsedElement, false, errorMsg, EMPTY_ARRAY );
  }
742210
function () {
				if (typeof global.onerror !== "undefined") {
					var self = this;
					global.onerror = function (msg, url, line) {
						self.error("[" + msg + " on line " + line + " of " + url + "]", 0);
					};
					return true;
				} else {
					return false;
				}
			}
440724
def checkError(barcode, whitelist, errors=1):
    '''
    
    '''

    near_matches = []
    comp_regex = regex.compile("(%s){e<=%i}" % (barcode, errors))
    b_length = len(barcode)
    for whitelisted_barcode in whitelist:
        w_length = len(whitelisted_barcode)

        # Don't check against itself
        if barcode == whitelisted_barcode:
            continue

        # If difference in barcode lengths > number of allowed errors, continue
        if (max(b_length, w_length) > (min(b_length, w_length) + errors)):
            continue
        if comp_regex.match(whitelisted_barcode):
            near_matches.append(whitelisted_barcode)

            # Assuming downstream processes are the same for
            # (>1 -> Inf) near_matches this is OK
            if len(near_matches) > 1:
                return near_matches

    return near_matches
1209773
function connectionCheck(error, diagnose) {
    var servers = diagnose.knownServers;

    // Nothing to check so we fail immediately.
    if (!servers || servers.length === 0) {
      throw new ServerDownError(error);
    }

    // We check all the servers that the user asked to check. If none respond,
    // we blame the network. Otherwise, we blame the server.
    return Promise.all(servers.map(function urlToAjax(url) {
      // eslint-disable-next-line no-use-before-define
      return ajax({ url: dedupURL(normalizeURL(url)), timeout: 1000 })
        .reflect();
    })).filter(function filterSuccessfulServers(result) {
      return result.isFulfilled();
    }).then(function checkAnyFullfilled(fulfilled) {
      if (fulfilled.length === 0) {
        throw new NetworkDownError(error);
      }

      throw new ServerDownError(error);
    });
  }
5259
def validate(self, error_message=None):
        

        if self.is_type():
            return

        if not error_message:
            error_message = "invalid value type"

        raise TypeError(
            "{}: expected={}, actual={}".format(error_message, self.typename, type(self._data))
        )