fix only terminate ffmpeg if instance exists

spotifyrecorder.py

@@ -226,24 +226,24 @@ def record(self, filename):
 
     # The blocking version of this method waits until the process is dead
     def stopBlocking(self):
-        # Remove from instances list
+        # Remove from instances list (and terminate)
         if self in self.instances:
             self.instances.remove(self)
 
-        # Send CTRL_C
-        self.process.terminate()
+            # Send CTRL_C
+            self.process.terminate()
 
-        print("[FFmpeg] [" + self.pid + "] terminated")
+            print("[FFmpeg] [" + self.pid + "] terminated")
 
-        # Sometimes this is not enough and ffmpeg survives, so we have to kill it after some time
-        time.sleep(1)
+            # Sometimes this is not enough and ffmpeg survives, so we have to kill it after some time
+            time.sleep(1)
 
-        if self.process.poll() == None:
-            # None means it has no return code (yet), with other words: it is still running
+            if self.process.poll() == None:
+                # None means it has no return code (yet), with other words: it is still running
 
-            self.process.kill()
+                self.process.kill()
 
-            print("[FFmpeg] [" + self.pid + "] killed")
+                print("[FFmpeg] [" + self.pid + "] killed")
 
         # Remove process from memory (and don't left a ffmpeg 'zombie' process)
         self.process = None