[checkupdates] UpdateCheckData warn if file was not found

Instead of throwing an exception.

fdroidserver/checkupdates.py

@@ -162,17 +162,25 @@ def check_tags(app, pattern):
             if app.UpdateCheckData:
                 filecode, codeex, filever, verex = app.UpdateCheckData.split('|')
                 vercode = None
-                if filecode:
-                    filecontent = (build_dir / filecode).read_text()
+                filecode = build_dir / filecode
+                if not filecode.is_file():
+                    logging.debug("UpdateCheckData file {0} not found in tag {1}".format(filecode, tag))
+                    continue
 
-                    m = re.search(codeex, filecontent)
-                    if m:
-                        vercode = m.group(1).strip()
+                filecontent = filecode.read_text()
+
+                m = re.search(codeex, filecontent)
+                if m:
+                    vercode = m.group(1).strip()
 
                 version = "??"
                 if filever:
                     if filever != '.':
-                        filecontent = (build_dir / filever).read_text()
+                        filever = build_dir / filever
+                        if filever.is_file():
+                            filecontent = filever.read_text()
+                        else:
+                            logging.debug("UpdateCheckData file {0} not found in tag {1}".format(filever, tag))
 
                     m = re.search(verex, filecontent)
                     if m:

tests/checkupdates.TestCase

@@ -212,8 +212,11 @@ class CheckupdatesTest(unittest.TestCase):
         vcs.latesttags.return_value = ['1.1.8', '1.1.9']
         with mock.patch(
             'pathlib.Path.read_text', lambda a: 'v1.1.9\nc10109'
-        ) as _ignored, mock.patch('fdroidserver.common.getvcs', return_value=vcs):
+        ) as _ignored, mock.patch.object(
+            Path, 'is_file'
+        ) as mock_path, mock.patch('fdroidserver.common.getvcs', return_value=vcs):
             _ignored  # silence the linters
+            mock_path.is_file.return_falue = True
             vername, vercode, _tag = fdroidserver.checkupdates.check_tags(app, None)
             self.assertEqual(vername, '1.1.9')
             self.assertEqual(vercode, '10109')