#803 Fix PR suggestions.

Author: yruslan

spark-cobol/src/main/scala/za/co/absa/cobrix/spark/cobol/source/streaming/FileStreamer.scala

@@ -32,6 +32,7 @@ import za.co.absa.cobrix.cobol.reader.common.Constants
   *
   * @param filePath   String containing the fully qualified path to the file.
   * @param fileSystem Underlying Hadoop file system.
+  * @note This class is not thread-safe and should only be accessed from a single thread
   * @throws IllegalArgumentException if the file is not found in the underlying file system.
   */
 class FileStreamer(filePath: String, fileSystem: FileSystem, startOffset: Long = 0L, maximumBytes: Long = 0L) extends SimpleStream {
@@ -110,8 +111,8 @@ class FileStreamer(filePath: String, fileSystem: FileSystem, startOffset: Long =
   }
 
   override def close(): Unit = {
+    wasOpened = true
     if (bufferedStream != null && !bufferedStream.isClosed) {
-      wasOpened = true
       bufferedStream.close()
       bufferedStream = null
     }