Catch error when release notes file could not be read

And show an error message to the user in that case.
This could happen if the user modified their installation or their resource folder.

Fixes Sentry issue CURA-2P2.

cura/UI/TextManager.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2019 Ultimaker B.V.
+# Copyright (c) 2021 Ultimaker B.V.
 # Cura is released under the terms of the LGPLv3 or higher.
 
 import collections
@@ -6,9 +6,11 @@ from typing import Optional, Dict, List, cast
 
 from PyQt5.QtCore import QObject, pyqtSlot
 
+from UM.i18n import i18nCatalog
 from UM.Resources import Resources
 from UM.Version import Version
 
+catalog = i18nCatalog("cura")
 
 #
 # This manager provides means to load texts to QML.
@@ -30,10 +32,11 @@ class TextManager(QObject):
         # Load change log texts and organize them with a dict
         try:
             file_path = Resources.getPath(Resources.Texts, "change_log.txt")
-        except FileNotFoundError:
+        except FileNotFoundError as e:
             # I have no idea how / when this happens, but we're getting crash reports about it.
-            return ""
+            return catalog.i18nc("@text:window", "The release notes could not be opened.") + "<br>" + str(e)
         change_logs_dict = {}  # type: Dict[Version, Dict[str, List[str]]]
+        try:
             with open(file_path, "r", encoding = "utf-8") as f:
                 open_version = None  # type: Optional[Version]
                 open_header = ""  # Initialise to an empty header in case there is no "*" in the first line of the changelog
@@ -54,6 +57,8 @@ class TextManager(QObject):
                         if open_header not in change_logs_dict[cast(Version, open_version)]:
                             change_logs_dict[cast(Version, open_version)][open_header] = []
                         change_logs_dict[cast(Version, open_version)][open_header].append(line)
+        except EnvironmentError as e:
+            return catalog.i18nc("@text:window", "The release notes could not be opened.") + "<br>" + str(e)
 
         # Format changelog text
         content = ""