disallow no values in configuration

This option could lead to missing warnings about missing or invalid
configuration values because code usually expects that values are exists
and not empty unless it is explicitly specified.

However, pacman configuration still requires this option in order to be
able to deal with boolean values

src/ahriman/application/handlers/setup.py

@@ -133,7 +133,9 @@ class Setup(Handler):
             repository(str): repository name
             paths(RepositoryPaths): repository paths instance
         """
-        configuration = Configuration()
+        # allow_no_value=True is required because pacman uses boolean configuration in which just keys present
+        # (e.g. NoProgressBar) which will lead to exception
+        configuration = Configuration(allow_no_value=True)
         # preserve case
         # stupid mypy thinks that it is impossible
         configuration.optionxform = lambda key: key  # type: ignore

src/ahriman/core/configuration.py

@@ -70,11 +70,15 @@ class Configuration(configparser.RawConfigParser):
     ARCHITECTURE_SPECIFIC_SECTIONS = ["build", "sign", "web"]
     SYSTEM_CONFIGURATION_PATH = Path(sys.prefix) / "share" / "ahriman" / "settings" / "ahriman.ini"
 
-    def __init__(self) -> None:
+    def __init__(self, allow_no_value: bool = False) -> None:
         """
         default constructor. In the most cases must not be called directly
+
+        Args:
+            allow_no_value(bool): copies ``configparser.RawConfigParser`` behaviour. In case if it is set to ``True``,
+                the keys without values will be allowed
         """
-        configparser.RawConfigParser.__init__(self, allow_no_value=True, converters={
+        configparser.RawConfigParser.__init__(self, allow_no_value=allow_no_value, converters={
             "list": self.__convert_list,
             "path": self.__convert_path,
         })

src/ahriman/core/report/report_trigger.py

@@ -43,7 +43,7 @@ class ReportTrigger(Trigger):
             configuration(Configuration): configuration instance
         """
         Trigger.__init__(self, architecture, configuration)
-        self.targets = configuration.getlist("report", "target")
+        self.targets = configuration.getlist("report", "target", fallback=[])
 
     def on_result(self, result: Result, packages: Iterable[Package]) -> None:
         """

src/ahriman/core/sign/gpg.py

@@ -97,7 +97,7 @@ class GPG(LazyLogging):
             Tuple[Set[SignSettings], Optional[str]]: tuple of sign targets and default PGP key
         """
         targets: Set[SignSettings] = set()
-        for option in configuration.getlist("sign", "target"):
+        for option in configuration.getlist("sign", "target", fallback=[]):
             target = SignSettings.from_option(option)
             if target == SignSettings.Disabled:
                 continue

src/ahriman/core/upload/http_upload.py

@@ -33,7 +33,7 @@ class HttpUpload(Upload):
     helper for the http based uploads
 
     Attributes:
-        auth(Tuple[str, str]): HTTP auth object
+        auth(Optional[Tuple[str, str]]): HTTP auth object if set
         timeout(int): HTTP request timeout in seconds
     """
 
@@ -47,9 +47,9 @@ class HttpUpload(Upload):
             section(str): configuration section name
         """
         Upload.__init__(self, architecture, configuration)
-        password = configuration.get(section, "password")
-        username = configuration.get(section, "username")
-        self.auth = (password, username)
+        password = configuration.get(section, "password", fallback=None)
+        username = configuration.get(section, "username", fallback=None)
+        self.auth = (password, username) if password and username else None
         self.timeout = configuration.getint(section, "timeout", fallback=30)
 
     @staticmethod

src/ahriman/core/upload/upload_trigger.py

@@ -43,7 +43,7 @@ class UploadTrigger(Trigger):
             configuration(Configuration): configuration instance
         """
         Trigger.__init__(self, architecture, configuration)
-        self.targets = configuration.getlist("upload", "target")
+        self.targets = configuration.getlist("upload", "target", fallback=[])
 
     def on_result(self, result: Result, packages: Iterable[Package]) -> None:
         """