diff --git a/cura/PickingPass.py b/cura/PickingPass.py
index bfe465ff39..75ee21ef41 100644
--- a/cura/PickingPass.py
+++ b/cura/PickingPass.py
@@ -69,6 +69,7 @@ class PickingPass(RenderPass):
     ## Get the world coordinates of a picked point
     def getPickedPosition(self, x: int, y: int) -> Vector:
         distance = self.getPickedDepth(x, y)
-        ray = self._scene.getActiveCamera().getRay(x, y)
-
-        return ray.getPointAlongRay(distance)
+        camera = self._scene.getActiveCamera()
+        if camera:
+            return camera.getRay(x, y).getPointAlongRay(distance)
+        return Vector()
diff --git a/cura/PrinterOutput/NetworkedPrinterOutputDevice.py b/cura/PrinterOutput/NetworkedPrinterOutputDevice.py
index 676157181b..b7862251c9 100644
--- a/cura/PrinterOutput/NetworkedPrinterOutputDevice.py
+++ b/cura/PrinterOutput/NetworkedPrinterOutputDevice.py
@@ -191,6 +191,7 @@ class NetworkedPrinterOutputDevice(PrinterOutputDevice):
     def put(self, target: str, data: str, on_finished: Optional[Callable[[QNetworkReply], None]]) -> None:
         if self._manager is None:
             self._createNetworkManager()
+        assert (self._manager is not None)
         request = self._createEmptyRequest(target)
         self._last_request_time = time()
         reply = self._manager.put(request, data.encode())
@@ -199,6 +200,7 @@ class NetworkedPrinterOutputDevice(PrinterOutputDevice):
     def get(self, target: str, on_finished: Optional[Callable[[QNetworkReply], None]]) -> None:
         if self._manager is None:
             self._createNetworkManager()
+        assert (self._manager is not None)
         request = self._createEmptyRequest(target)
         self._last_request_time = time()
         reply = self._manager.get(request)
@@ -207,6 +209,7 @@ class NetworkedPrinterOutputDevice(PrinterOutputDevice):
     def post(self, target: str, data: str, on_finished: Optional[Callable[[QNetworkReply], None]], on_progress: Callable = None) -> None:
         if self._manager is None:
             self._createNetworkManager()
+        assert (self._manager is not None)
         request = self._createEmptyRequest(target)
         self._last_request_time = time()
         reply = self._manager.post(request, data)
@@ -218,6 +221,7 @@ class NetworkedPrinterOutputDevice(PrinterOutputDevice):
 
         if self._manager is None:
             self._createNetworkManager()
+        assert (self._manager is not None)
         request = self._createEmptyRequest(target, content_type=None)
         multi_post_part = QHttpMultiPart(QHttpMultiPart.FormDataType)
         for part in parts:
diff --git a/cura/Settings/ContainerManager.py b/cura/Settings/ContainerManager.py
index 12f5b6b0a3..657329aad4 100644
--- a/cura/Settings/ContainerManager.py
+++ b/cura/Settings/ContainerManager.py
@@ -208,7 +208,6 @@ class ContainerManager(QObject):
         if not file_url:
             return {"status": "error", "message": "Invalid path"}
 
-        mime_type = None
         if file_type not in self._container_name_filters:
             try:
                 mime_type = MimeTypeDatabase.getMimeTypeForFile(file_url)
diff --git a/plugins/SupportEraser/SupportEraser.py b/plugins/SupportEraser/SupportEraser.py
index 92b42f9abc..44d4831c04 100644
--- a/plugins/SupportEraser/SupportEraser.py
+++ b/plugins/SupportEraser/SupportEraser.py
@@ -4,6 +4,7 @@
 from PyQt5.QtCore import Qt, QTimer
 from PyQt5.QtWidgets import QApplication
 
+from UM.Application import Application
 from UM.Math.Vector import Vector
 from UM.Tool import Tool
 from UM.Event import Event, MouseEvent