JS Regex.find does not throw on invalid start index #KT-36082

libraries/stdlib/js/src/kotlin/text/regex.kt

@@ -70,9 +70,15 @@ public actual class Regex actual constructor(pattern: String, options: Set<Regex
      *
      * @param startIndex An index to start search with, by default 0. Must be not less than zero and not greater than `input.length()`
      * @return An instance of [MatchResult] if match was found or `null` otherwise.
+     * @throws IndexOutOfBoundsException if [startIndex] is less than zero or greater than the length of the [input] char sequence.
      */
     @Suppress("ACTUAL_FUNCTION_WITH_DEFAULT_ARGUMENTS")
-    public actual fun find(input: CharSequence, startIndex: Int = 0): MatchResult? = nativePattern.findNext(input.toString(), startIndex)
+    public actual fun find(input: CharSequence, startIndex: Int = 0): MatchResult? {
+        if (startIndex < 0 || startIndex > input.length) {
+            throw IndexOutOfBoundsException("Start index out of bounds: $startIndex, input length: ${input.length}")
+        }
+        return nativePattern.findNext(input.toString(), startIndex)
+    }
 
     /**
      * Returns a sequence of all occurrences of a regular expression within the [input] string, beginning at the specified [startIndex].

libraries/stdlib/test/text/RegexTest.kt

@@ -48,6 +48,10 @@ class RegexTest {
 
         val noMatch = last.next()
         assertEquals(null, noMatch)
+
+        assertFailsWith<IndexOutOfBoundsException> { p.find(input, -1) }
+        assertFailsWith<IndexOutOfBoundsException> { p.find(input, input.length + 1) }
+        assertEquals(null, p.find(input, input.length))
     }
 
     @Test fun matchIgnoreCase() {
@@ -82,6 +86,7 @@ class RegexTest {
         assertEquals(2, matches.size)
 
         assertEquals("", pattern.findAll(input, input.length).single().value)
+        assertEquals("", pattern.find(input, input.length)?.value)
     }
 
     @Test fun matchGroups() {