fix: Always return a string or None from ObjectNode.module_path

PR-419: #419
Co-authored-by: Timothée Mazzucotelli <dev@pawamoy.fr>

Author: mnesarco

src/griffe/_internal/agents/nodes/runtime.py

@@ -6,7 +6,7 @@
 import sys
 import typing
 from functools import cached_property
-from types import GetSetDescriptorType
+from types import GetSetDescriptorType, ModuleType
 from typing import TYPE_CHECKING, Any, ClassVar
 
 from griffe._internal.enumerations import ObjectKind
@@ -106,7 +106,7 @@ def module(self) -> ObjectNode:
     def module_path(self) -> str | None:
         """The object's module path."""
         try:
-            return self.obj.__module__
+            module = self.obj.__module__
         except AttributeError:
             try:
                 module = inspect.getmodule(self.obj) or self.module.obj
@@ -116,6 +116,27 @@ def module_path(self) -> str | None:
                 return module.__spec__.name  # type: ignore[union-attr]
             except AttributeError:
                 return getattr(module, "__name__", None)
+        else:
+            # Some libraries mistakenly set `__module__` to a module object instead of a string.
+            # Handle this case specifically, but do not cast any other object to a string.
+            if isinstance(module, ModuleType):
+                logger.debug(
+                    "Object %s has its `__module__` attribute set to a module object: "
+                    "it must be a string instead (the module fully qualified name). "
+                    "Please report to the maintainers of this library.",
+                    self.path,
+                )
+                return getattr(module, "__qualname__", getattr(module, "__name__", None))
+            if isinstance(module, str):
+                return module
+            logger.debug(
+                "Object %s has its `__module__` attribute set to a %s object: "
+                "it must be a string instead (the module fully qualified name). "
+                "Please report to the maintainers of this library.",
+                self.path,
+                getattr(type(module), "__name__", str(type(module))),
+            )
+            return None
 
     @property
     def kind(self) -> ObjectKind: