Make AbstractJsonPatternParser throw an exception for invalid pattern instead of logging an ERROR status

README.md

@@ -2409,6 +2409,9 @@ LOGGER.info("{\"type\":\"example\",\"msg\":\"example of json message with type\"
 Note that the value that is sent for `line_long` is a number even though in your pattern it is a quoted text.
 And the json_message field value is a json object, not a string.
 
+You can escape an operation by prefixing it with `\` if you don't want it to be interpreted.
+
+
 #### Omitting fields with empty values
 
 The pattern provider can be configured to omit fields with the following _empty_ values:

src/main/java/net/logstash/logback/composite/AbstractPatternJsonProvider.java

@@ -19,6 +19,7 @@
 import java.util.Objects;
 
 import net.logstash.logback.pattern.AbstractJsonPatternParser;
+import net.logstash.logback.pattern.AbstractJsonPatternParser.JsonPatternException;
 import net.logstash.logback.pattern.NodeWriter;
 
 import ch.qos.logback.access.spi.IAccessEvent;
@@ -79,19 +80,28 @@ public void start() {
         if (jsonFactory == null) {
             throw new IllegalStateException("JsonFactory has not been set");
         }
-        initializeNodeWriter();
+
+        try {
+            this.nodeWriter = initializeNodeWriter();
+        } catch (JsonPatternException e) {
+            this.nodeWriter = null;
+            addError("Invalid [pattern]: " + e.getMessage(), e);
+        }
 
         super.start();
     }
 
 
     /**
      * Parses the pattern into a {@link NodeWriter}.
+     * 
+     * @return a {@link NodeWriter}
+     * @throws JsonPatternException thrown in case of invalid pattern
      */
-    private void initializeNodeWriter() {
+    private NodeWriter<Event> initializeNodeWriter() throws JsonPatternException {
         AbstractJsonPatternParser<Event> parser = createParser(this.jsonFactory);
         parser.setOmitEmptyFields(omitEmptyFields);
-        this.nodeWriter = parser.parse(pattern);
+        return parser.parse(pattern);
     }
 
 

src/main/java/net/logstash/logback/composite/accessevent/AccessEventPatternJsonProvider.java

@@ -29,7 +29,7 @@ public class AccessEventPatternJsonProvider extends AbstractPatternJsonProvider<
 
     @Override
     protected AbstractJsonPatternParser<IAccessEvent> createParser(JsonFactory jsonFactory) {
-        return new AccessEventJsonPatternParser(this, jsonFactory);
+        return new AccessEventJsonPatternParser(getContext(), jsonFactory);
     }
 
 }

src/main/java/net/logstash/logback/composite/loggingevent/LoggingEventPatternJsonProvider.java

@@ -29,7 +29,7 @@ public class LoggingEventPatternJsonProvider extends AbstractPatternJsonProvider
 
     @Override
     protected AbstractJsonPatternParser<ILoggingEvent> createParser(JsonFactory jsonFactory) {
-        return new LoggingEventJsonPatternParser(this, jsonFactory);
+        return new LoggingEventJsonPatternParser(getContext(), jsonFactory);
     }
 
 }