Resolve NPE when Ids don't have associated configuration elements

This fixes a regression introduced in 34b8e38
When that commit was done some instanceof checks were removed.
The result of removing the instanceof checks had the side effect
of removing the implicit null check that instanceof essentially
does.

This change restores the null check for when IConfigurationElement
is null.

Fixes #1608

Author: jonahgraham

ui/org.eclipse.pde.ui/src/org/eclipse/pde/internal/ui/editor/plugin/rows/IdAttributeRow.java

@@ -53,26 +53,28 @@ public String getText(Object element) {
 				Entry<String, IConfigurationElement> entry = (Entry<String, IConfigurationElement>) element;
 				String text = entry.getKey();
 				IConfigurationElement value = entry.getValue();
-				String name = value.getAttribute("name"); //$NON-NLS-1$
-				if (name == null) {
-					name = value.getAttribute("label"); //$NON-NLS-1$
+				if (value != null) {
+					String name = value.getAttribute("name"); //$NON-NLS-1$
 					if (name == null) {
-						name = value.getAttribute("description"); //$NON-NLS-1$
+						name = value.getAttribute("label"); //$NON-NLS-1$
+						if (name == null) {
+							name = value.getAttribute("description"); //$NON-NLS-1$
+						}
 					}
-				}
 
-				String contributor = value.getContributor().getName();
+					String contributor = value.getContributor().getName();
 
-				if (input != null && name != null && name.startsWith("%") && contributor != null) { //$NON-NLS-1$
-					IPluginModelBase model = PluginRegistry.findModel(contributor);
-					name = model.getResourceString(name);
-				}
+					if (input != null && name != null && name.startsWith("%") && contributor != null) { //$NON-NLS-1$
+						IPluginModelBase model = PluginRegistry.findModel(contributor);
+						name = model.getResourceString(name);
+					}
 
-				if (name != null) {
-					text += " - " + name; //$NON-NLS-1$
-				}
-				if (contributor != null) {
-					text += " [" + contributor + "]"; //$NON-NLS-1$ //$NON-NLS-2$
+					if (name != null) {
+						text += " - " + name; //$NON-NLS-1$
+					}
+					if (contributor != null) {
+						text += " [" + contributor + "]"; //$NON-NLS-1$ //$NON-NLS-2$
+					}
 				}
 				return text;
 			}