Add flake8 docstring plugin, formatting, create base class for embeds & models

didier/exceptions/config.py

@@ -0,0 +1,12 @@
+__all__ = ["MissingEnvironmentVariable"]
+
+
+class MissingEnvironmentVariable(RuntimeError):
+    """Exception raised when an environment variable is missing
+
+    These are not necessarily checked on startup, because they may be unused
+    during a given test run, and random unrelated crashes would be annoying
+    """
+
+    def __init__(self, variable: str):
+        super().__init__(f"Missing environment variable: {variable}")