fix: null range on DocumentSymbolData (#831)

fix: null range on DocumentSymbolData 

Fixes #830

src/main/java/com/redhat/devtools/lsp4ij/features/documentSymbol/DocumentSymbolData.java

@@ -10,18 +10,21 @@
  ******************************************************************************/
 package com.redhat.devtools.lsp4ij.features.documentSymbol;
 
+import javax.swing.Icon;
+
 import com.intellij.openapi.project.Project;
+import com.intellij.openapi.util.TextRange;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
 import com.intellij.psi.impl.FakePsiElement;
+import com.redhat.devtools.lsp4ij.LSPIJUtils;
 import com.redhat.devtools.lsp4ij.LanguageServerItem;
 import com.redhat.devtools.lsp4ij.client.features.LSPClientFeatures;
+
 import org.eclipse.lsp4j.DocumentSymbol;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import javax.swing.*;
-
 
 /**
  * LSP document symbol data.
@@ -34,6 +37,7 @@ public class DocumentSymbolData extends FakePsiElement {
     private final @NotNull PsiFile psiFile;
     private final DocumentSymbolData parent;
     private final @NotNull LanguageServerItem languageServer;
+    private TextRange textRange;
     private DocumentSymbolData[] cachedChildren;
 
     public DocumentSymbolData(@NotNull DocumentSymbol documentSymbol,
@@ -76,6 +80,14 @@ public int getTextOffset() {
         return getClientFeatures().getDocumentSymbolFeature().getTextOffset(documentSymbol, psiFile);
     }
 
+    @Override
+    public TextRange getTextRange() {
+        if (textRange == null) {
+            this.textRange = LSPIJUtils.toTextRange(documentSymbol.getRange(), LSPIJUtils.getDocument(psiFile.getVirtualFile()));
+        }
+        return textRange;
+    }
+
     @Override
     public void navigate(boolean requestFocus) {
         getClientFeatures().getDocumentSymbolFeature().navigate(documentSymbol, psiFile, requestFocus);