Improve precondition checks

Author: circusmagnus

kotlinx-coroutines-core/common/src/internal/RingBuffer.kt

@@ -12,7 +12,7 @@ internal class RingBuffer<T>(val capacity: Int) : AbstractList<T>(), RandomAcces
         private set
 
     override fun get(index: Int): T {
-        require(index in 0 until size)
+        require(index in 0 until size) { "Index out of bounds: $index" }
         @Suppress("UNCHECKED_CAST")
         return buffer[startIndex.forward(index)] as T
     }
@@ -70,9 +70,7 @@ internal class RingBuffer<T>(val capacity: Int) : AbstractList<T>(), RandomAcces
      * Add [element] to the buffer or fail with [IllegalStateException] if no free space available in the buffer
      */
     fun add(element: T) {
-        if (isFull()) {
-            throw IllegalStateException("ring buffer is full")
-        }
+        check(!isFull()) { "Ring buffer is full" }
 
         buffer[startIndex.forward(size)] = element
         size++