Add more unhappy-path tests

One for the new setting_version. One for the misconception of version numbers being a major-minor version or something, because it's not stored that way.

Contributes to issue CURA-3427.

plugins/VersionUpgrade/VersionUpgrade25to26/tests/TestVersionUpgrade25to26.py

@@ -95,6 +95,22 @@ true = false
         "test_name": "Not a Number",
         "file_data": """[general]
 version = not-a-text-version-number
+""",
+        "exception": ValueError
+    },
+    {
+        "test_name": "Setting Value NaN",
+        "file_data": """[general]
+version = 4
+[metadata]
+setting_version = latest_or_something
+""",
+        "exception": ValueError
+    },
+    {
+        "test_name": "Major-Minor",
+        "file_data": """[general]
+version = 1.2
 """,
         "exception": ValueError
     }