stream: don't wrap exceptions in ByteStringParser (#31311)

akka-remote/src/test/scala/akka/remote/artery/tcp/TcpFramingSpec.scala

@@ -7,7 +7,6 @@ package tcp
 
 import scala.util.Random
 
-import akka.stream.impl.io.ByteStringParser.ParsingException
 import akka.stream.scaladsl.Flow
 import akka.stream.scaladsl.Framing.FramingException
 import akka.stream.scaladsl.Sink
@@ -62,8 +61,7 @@ class TcpFramingSpec extends AkkaSpec("""
     "reject invalid magic" in {
       val bytes = frameBytes(2)
       val fail = Source(List(bytes)).via(framingFlow).runWith(Sink.seq).failed.futureValue
-      fail shouldBe a[ParsingException]
-      fail.getCause shouldBe a[FramingException]
+      fail shouldBe a[FramingException]
     }
 
     "include streamId in each frame" in {

akka-stream/src/main/scala/akka/stream/impl/io/ByteStringParser.scala

@@ -80,7 +80,7 @@ import akka.util.ByteString
 
             DontRecurse
           case NonFatal(ex) =>
-            failStage(new ParsingException(s"Parsing failed in step $current", ex))
+            failStage(ex)
 
             DontRecurse
         }
@@ -177,6 +177,7 @@ import akka.util.ByteString
       throw new IllegalStateException("no initial parser installed: you must use startWith(...)")
   }
 
+  @deprecated("Deprecated for internal usage. Will not be emitted any more.", "2.6.20")
   class ParsingException(msg: String, cause: Throwable) extends RuntimeException(msg, cause)
 
   val NeedMoreData = new Exception with NoStackTrace