refactor: minor cleanups

antlr-kotlin-runtime/src/commonMain/kotlin/org/antlr/v4/kotlinruntime/Parser.kt

@@ -49,8 +49,10 @@ public abstract class Parser(input: TokenStream) : Recognizer<Token, ParserATNSi
     }
 
     override fun exitEveryRule(ctx: ParserRuleContext) {
-      if (ctx.children is ArrayList<*>) {
-        (ctx.children as ArrayList<*>).trimToSize()
+      val children = ctx.children
+
+      if (children is ArrayList<*>) {
+        children.trimToSize()
       }
     }
   }

antlr-kotlin-runtime/src/commonMain/kotlin/org/antlr/v4/kotlinruntime/Token.kt

@@ -117,10 +117,8 @@ public interface Token {
   public fun startPoint(): Point =
     Point(line, charPositionInLine)
 
-  public fun endPoint(): Point? =
-    if (text == null) {
-      null
-    } else {
-      Point(line, charPositionInLine).advance(text!!)
-    }
+  public fun endPoint(): Point? {
+    val text = this.text ?: return null
+    return Point(line, charPositionInLine).advance(text)
+  }
 }

antlr-kotlin-runtime/src/commonMain/kotlin/org/antlr/v4/kotlinruntime/tree/IterativeParseTreeWalker.kt

@@ -57,7 +57,11 @@ public open class IterativeParseTreeWalker : ParseTreeWalker() {
         // No next, sibling, so move up
         currentNode = nodeStack.removeFirst()
         currentIndex = indexStack.pop()
-      } while (currentNode != null)
+
+        // The original condition was 'currentNode != null',
+        // but since nodeStack.removeFirst() throws if there
+        // is no element, the condition is always true
+      } while (true)
     }
   }
 }