Issue #18919: If the close() method of a writer in the sunau or wave module
failed, second invocation of close() and destructor no more raise an
exception.
diff --git a/Lib/sunau.py b/Lib/sunau.py
index 5212370..15f7b03 100644
--- a/Lib/sunau.py
+++ b/Lib/sunau.py
@@ -414,14 +414,17 @@
             self._patchheader()
 
     def close(self):
-        self._ensure_header_written()
-        if self._nframeswritten != self._nframes or \
-                  self._datalength != self._datawritten:
-            self._patchheader()
-        self._file.flush()
-        if self._opened and self._file:
-            self._file.close()
-        self._file = None
+        if self._file:
+            try:
+                self._ensure_header_written()
+                if self._nframeswritten != self._nframes or \
+                        self._datalength != self._datawritten:
+                    self._patchheader()
+                self._file.flush()
+                if self._opened and self._file:
+                    self._file.close()
+            finally:
+                self._file = None
 
     #
     # private methods
diff --git a/Lib/wave.py b/Lib/wave.py
index 54f0302..2c386a5 100644
--- a/Lib/wave.py
+++ b/Lib/wave.py
@@ -436,11 +436,13 @@
 
     def close(self):
         if self._file:
-            self._ensure_header_written(0)
-            if self._datalength != self._datawritten:
-                self._patchheader()
-            self._file.flush()
-            self._file = None
+            try:
+                self._ensure_header_written(0)
+                if self._datalength != self._datawritten:
+                    self._patchheader()
+                self._file.flush()
+            finally:
+                self._file = None
         if self._i_opened_the_file:
             self._i_opened_the_file.close()
             self._i_opened_the_file = None