FELIX-6500 : Fixed NPE. (#149)

Co-authored-by: Manfred Baedke <manfred.baedke@greenbytes.de>
diff --git a/webconsole/src/main/java/org/apache/felix/webconsole/internal/configuration/ConfigJsonSupport.java b/webconsole/src/main/java/org/apache/felix/webconsole/internal/configuration/ConfigJsonSupport.java
index 760101a..323ac13 100644
--- a/webconsole/src/main/java/org/apache/felix/webconsole/internal/configuration/ConfigJsonSupport.java
+++ b/webconsole/src/main/java/org/apache/felix/webconsole/internal/configuration/ConfigJsonSupport.java
@@ -350,7 +350,7 @@
 
                 final Configuration c = ConfigurationUtil.findConfiguration( this.configurationAdmin, id );
                 Configuration config = c;
-                if (!this.configurationHandlers.isEmpty()) {
+                if (null != config && !this.configurationHandlers.isEmpty()) {
                     for(final ConfigurationHandler handler : this.configurationHandlers) {
                         if (!handler.listConfiguration(config.getFactoryPid(), config.getPid())) {
                             config = null;