Catch environment errors when reading license file from package

The package may be inaccessible for whatever reason, which would crash Cura.

New attempt to fix CURA-2RP (without breaking the unit test saying that this error should be raised by Uranium then).

plugins/Toolbox/src/CloudSync/LicensePresenter.py

@@ -1,3 +1,6 @@
+# Copyright (c) 2021 Ultimaker B.V.
+# Cura is released under the terms of the LGPLv3 or higher.
+
 import os
 from collections import OrderedDict
 from typing import Dict, Optional, List, Any
@@ -95,7 +98,11 @@ class LicensePresenter(QObject):
 
         for package_id, item in packages.items():
             item["package_id"] = package_id
+            try:
                 item["licence_content"] = self._package_manager.getPackageLicense(item["package_path"])
+            except EnvironmentError as e:
+                Logger.error(f"Could not open downloaded package {package_id} to read license file! {type(e)} - {e}")
+                continue  # Skip this package.
             if item["licence_content"] is None:
                 # Implicitly accept when there is no license
                 item["accepted"] = True

plugins/Toolbox/src/Toolbox.py

@@ -682,9 +682,13 @@ class Toolbox(QObject, Extension):
         if not package_info:
             Logger.log("w", "Package file [%s] was not a valid CuraPackage.", file_path)
             return
-
-        license_content = self._package_manager.getPackageLicense(file_path)
         package_id = package_info["package_id"]
+
+        try:
+            license_content = self._package_manager.getPackageLicense(file_path)
+        except EnvironmentError as e:
+            Logger.error(f"Could not open downloaded package {package_id} to read license file! {type(e)} - {e}")
+            return
         if license_content is not None:
             # get the icon url for package_id, make sure the result is a string, never None
             icon_url = next((x["icon_url"] for x in self.packagesModel.items if x["id"] == package_id), None) or ""