http upload: do not crash on invalid slot responses

src/main/java/eu/siacs/conversations/http/HttpUploadConnection.java

@@ -145,11 +145,11 @@ public class HttpUploadConnection implements Transferable {
 									}
 								}
 							}
-						}
 							if (!canceled) {
 								new Thread(this::upload).start();
 							}
 							return;
+						}
 					} catch (MalformedURLException e) {
 						//fall through
 					}
@@ -229,7 +229,9 @@ public class HttpUploadConnection implements Transferable {
 			if (connection != null) {
 				connection.disconnect();
 			}
+			if (wakeLock.isHeld()) {
 				wakeLock.release();
 			}
 		}
+	}
 }