feat: domain, use cases and JSON repository with file error handling

Task: MIL-002#1
Task: MIL-002#2
Task: MIL-002#3
Task: MIL-002#4

src/password_manager/domain/errors.py

@@ -0,0 +1,32 @@
+"""@brief Errors raised by the business rules of the password manager.
+
+@file errors.py
+"""
+
+
+class PasswordManagerError(Exception):
+    """@brief Base class of every error the password manager raises on purpose."""
+
+
+class EmptyFieldError(PasswordManagerError):
+    """@brief A required field was left empty."""
+
+
+class DataFileNotFoundError(PasswordManagerError):
+    """@brief The data file does not exist, so nothing can be looked up."""
+
+
+class InvalidDataFileError(PasswordManagerError):
+    """@brief The data file exists but does not hold the expected structure."""
+
+
+class EntryNotFoundError(PasswordManagerError):
+    """@brief No entry is stored for a website."""
+
+    def __init__(self, website: str) -> None:
+        """@brief Create the error.
+
+        @param website The website that was looked up.
+        """
+        super().__init__(website)
+        self.website = website