Fix NullPointerException in logger when message is null (#12588)

LogSection.publish and VConsole.log/VConsole.error methods now replace
null message with an empty string ("")

Change-Id: I735b51bce971ababe2557f1b6c317c01066bc03c

client/src/com/vaadin/client/VConsole.java

 
     public static void log(String msg) {
         if (LogConfiguration.loggingIsEnabled(Level.INFO)) {
-            getLogger().log(Level.INFO, msg);
+            // Check for null, so no NullPointerException is generated when
+            // formatting (#12588)
+            getLogger().log(Level.INFO, msg == null ? "null" : msg);
         }
     }
 
     public static void log(Throwable e) {
         if (LogConfiguration.loggingIsEnabled(Level.INFO)) {
-            getLogger().log(Level.INFO, e.getMessage(), e);
+            // Check for null, so no NullPointerException is generated when
+            // formatting (#12588)
+            getLogger().log(Level.INFO,
+                    e.getMessage() == null ? "" : e.getMessage(), e);
         }
     }
 
     public static void error(Throwable e) {
         if (LogConfiguration.loggingIsEnabled(Level.SEVERE)) {
-            getLogger().log(Level.SEVERE, e.getMessage(), e);
+            // Check for null, so no NullPointerException is generated when
+            // formatting (#12588)
+            getLogger().log(Level.SEVERE,
+                    e.getMessage() == null ? "" : e.getMessage(), e);
         }
     }
 
     public static void error(String msg) {
         if (LogConfiguration.loggingIsEnabled(Level.SEVERE)) {
-            getLogger().log(Level.SEVERE, msg);
+            // Check for null, so no NullPointerException is generated when
+            // formatting (#12588)
+            getLogger().log(Level.SEVERE, msg == null ? "null" : msg);
         }
     }
 

client/src/com/vaadin/client/debug/internal/LogSection.java

                 return;
             }
 
+            // If no message is provided, record.getMessage will be null and so
+            // the formatter.format will fail with NullPointerException (#12588)
+            if (record.getMessage() == null) {
+                record.setMessage("");
+            }
+
             Formatter formatter = getFormatter();
             String msg = formatter.format(record);