Fix out of bounds exception

src/test/java/org/jetbrains/plugins/ideavim/action/motion/text/MotionSentenceNextStartActionTest.kt

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2003-2023 The IdeaVim authors
+ *
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE.txt file or at
+ * https://opensource.org/licenses/MIT.
+ */
+
+package org.jetbrains.plugins.ideavim.action.motion.text
+
+import com.maddyhome.idea.vim.command.VimStateMachine
+import org.jetbrains.plugins.ideavim.VimTestCase
+import org.junit.jupiter.api.Test
+
+class MotionSentenceNextStartActionTest : VimTestCase() {
+  @Test
+  fun `test with two empty lines`() {
+    doTest(
+      "C<CR><S-Left><C-Right><C-O>)",
+      """
+        Lorem ipsum dolor sit amet,
+        consectetur adipiscing elit
+        Sed in orci mauris.
+        Cras id tellus in ${c}ex imperdiet egestas.
+      """.trimIndent(),
+      """
+        Lorem ipsum dolor sit amet,
+        consectetur adipiscing elit
+        Sed in orci mauris.
+        Cras id tellus in 
+        
+      """.trimIndent(),
+      VimStateMachine.Mode.INSERT,
+      VimStateMachine.SubMode.NONE,
+    )
+  }
+}

vim-engine/src/main/kotlin/com/maddyhome/idea/vim/api/VimSearchHelperBase.kt

@@ -526,7 +526,7 @@ public abstract class VimSearchHelperBase : VimSearchHelper {
       end?.let { findSentenceEnd(editor, chars, it - 1, max, dir, countCurrent) }
     }
     var res: Int? = null
-    if (end != null && (chars[end] != '\n' || !countCurrent)) {
+    if (end != null && end < chars.length && (chars[end] != '\n' || !countCurrent)) {
       res = end + 1
       while (res < max) {
         val ch = chars[res]