don't show useless system error message when unresolved relative URL is clicked at in Quick Doc

platform/lang-impl/src/com/intellij/codeInsight/documentation/DocumentationManager.java

@@ -952,11 +952,15 @@ public class DocumentationManager extends DockablePopupManager<DocumentationComp
                 );
                 String url1 = urls != null && !urls.isEmpty() ? urls.get(0) : url;
                 BrowserUtil.browse(url1);
+                return "";
+              }
+              else if (url.startsWith("..")) {
+                return CodeInsightBundle.message("javadoc.error.resolving.url", url);
               }
               else {
                 BrowserUtil.browse(url);
+                return "";
               }
-              return "";
             }
 
             @Override

platform/platform-resources-en/src/messages/CodeInsightBundle.properties

@@ -518,3 +518,4 @@ dialog.edit.template.checkbox.xsl.text=XSL Text
 highlight.imported.classes.chooser.title=Choose Imported Classes to Highlight
 highlight.imported.members.chooser.title=Choose Imported Members to Highlight
 javadoc.resolved.value=Resolved value\: 
+javadoc.error.resolving.url=Couldn''t resolve URL <i>{0}</i> <p>Configuring paths to API docs in <a href="open://Project Settings">project settings</a> might help