refactor(GUI & parser): improve code structure and error handling

- Refactor `DisplayComponent` to use direct assignment for selection.
- Add `SwingUtilities` import for clarity.
- Enhance `CodeUtil` with try-catch for extension lookup to handle exceptions.

Author: phodal

core/src/main/kotlin/cc/unitmesh/devti/gui/component/DisplayComponent.kt

@@ -2,10 +2,11 @@ package cc.unitmesh.devti.gui.component
 
 import com.intellij.util.ui.JBEmptyBorder
 import com.intellij.util.ui.UIUtil
-import javax.accessibility.AccessibleContext
-import javax.swing.JEditorPane
 import org.apache.commons.text.StringEscapeUtils
 import org.jsoup.Jsoup
+import javax.accessibility.AccessibleContext
+import javax.swing.JEditorPane
+import javax.swing.SwingUtilities
 
 class DisplayComponent(question: String) : JEditorPane() {
     init {
@@ -32,8 +33,8 @@ class DisplayComponent(question: String) : JEditorPane() {
         this.text = content
         if (selectionStart != selectionEnd) {
             SwingUtilities.invokeLater {
-                this.setSelectionStart(selectionStart)
-                this.setSelectionEnd(selectionEnd)
+                this.selectionStart = selectionStart
+                this.selectionEnd = selectionEnd
             }
         }
     }

core/src/main/kotlin/cc/unitmesh/devti/util/parser/CodeUtil.kt

@@ -32,8 +32,11 @@ class CodeFence(val language: Language, val text: String, val isComplete: Boolea
 
             val trimmedCode = codeBuilder.trim().toString()
             val language = findLanguage(languageId ?: "")
-            val extension =
+            val extension = try {
                 language.associatedFileType?.defaultExtension ?: lookupFileExt(languageId ?: "txt")
+            } catch (e: Exception) {
+                lookupFileExt(languageId ?: "txt")
+            }
 
             return if (trimmedCode.isEmpty()) {
                 CodeFence(language, "", codeClosed, extension)

core/src/test/kotlin/cc/unitmesh/devti/gui/chat/MessageViewTest.kt

@@ -77,4 +77,4 @@ class MessageViewTest {
             |}
             |```""".trimMargin())
     }
-}
+}