Add null check to exception cause logging (#144)

Author: Vladimir Ilyin

ui/jetbrains/src/main/java/com/neueda/jetbrains/plugin/graphdb/jetbrains/services/ExecutorServiceImpl.java

@@ -2,12 +2,15 @@
 
 import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.application.ModalityState;
+import com.intellij.openapi.diagnostic.Logger;
 
 import java.util.concurrent.Callable;
 import java.util.function.Consumer;
 
 public class ExecutorServiceImpl implements ExecutorService {
 
+    private static final Logger LOG = Logger.getInstance(ExecutorServiceImpl.class);
+
     @Override
     public <T> void runInBackground(Callable<T> task, Consumer<T> onSuccess, Consumer<Exception> onFailure) {
         runInBackground(task, onSuccess, onFailure, ModalityState.defaultModalityState());
@@ -21,7 +24,14 @@ public <T> void runInBackground(Callable<T> task, Consumer<T> onSuccess, Consume
                 ApplicationManager.getApplication().invokeLater(() -> onSuccess.accept(result), modalityState);
 
             } catch (Exception exception) {
-                ApplicationManager.getApplication().invokeLater(() -> onFailure.accept(exception), modalityState);
+                ApplicationManager.getApplication().invokeLater(() -> {
+                    try {
+                        onFailure.accept(exception);
+                    } catch (Exception handlerException) {
+                        LOG.error("Exception in background execution error handler:", handlerException);
+                        LOG.error("Original exception:", exception);
+                    }
+                }, modalityState);
             }
         });
     }

ui/jetbrains/src/main/java/com/neueda/jetbrains/plugin/graphdb/jetbrains/ui/console/log/LogPanel.java

@@ -15,6 +15,7 @@
 import com.neueda.jetbrains.plugin.graphdb.jetbrains.ui.console.event.QueryExecutionProcessEvent;
 import com.neueda.jetbrains.plugin.graphdb.jetbrains.ui.console.event.QueryParametersRetrievalErrorEvent;
 import com.neueda.jetbrains.plugin.graphdb.jetbrains.ui.datasource.metadata.MetadataRetrieveEvent;
+import org.jetbrains.annotations.Nullable;
 
 import java.awt.*;
 import java.util.Map;
@@ -135,8 +136,10 @@ public void info(String message) {
         log.print(message, ConsoleViewContentType.NORMAL_OUTPUT);
     }
 
-    public void error(String message) {
-        log.print(message, ConsoleViewContentType.ERROR_OUTPUT);
+    public void error(@Nullable String message) {
+        if (message != null) {
+            log.print(message, ConsoleViewContentType.ERROR_OUTPUT);
+        }
     }
 
     public void printException(Exception exception) {