Fix sinks with onException() handler

It is possible to call onException() even after onFinish(), in case of
onFinish() throws, and in this case onException() should be no-op for
such sinks.

Also there can be caveats with PartitionedSync.

Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>

src/Storages/HDFS/StorageHDFS.cpp

@@ -418,6 +418,8 @@ public:
 
     void onException() override
     {
+        if (!writer)
+            return;
         onFinish();
     }
 

src/Storages/StorageFile.cpp

@@ -812,6 +812,8 @@ public:
 
     void onException() override
     {
+        if (!writer)
+            return;
         onFinish();
     }
 

src/Storages/StorageS3.cpp

@@ -603,6 +603,8 @@ public:
 
     void onException() override
     {
+        if (!writer)
+            return;
         onFinish();
     }
 

src/Storages/StorageURL.cpp

@@ -445,6 +445,8 @@ void StorageURLSink::consume(Chunk chunk)
 
 void StorageURLSink::onException()
 {
+    if (!writer)
+        return;
     onFinish();
 }