feat: improve error messages for annotation issues in command parameters

changelog/1411.feature.rst

@@ -0,0 +1 @@
+Improve error messaging when a command's annotation is stringified.

disnake/ext/commands/core.py

@@ -391,7 +391,14 @@ def callback(self, function: CommandCallback[CogT, Any, P, T]) -> None:
         except AttributeError:
             globalns = {}
 
-        params = get_signature_parameters(function, globalns, skip_standard_params=True)
+        try:
+            params = get_signature_parameters(function, globalns, skip_standard_params=True)
+        except NameError as e:
+            raise NameError(
+                "Stringified params annotations must have their reference imported outside of a TYPE_CHECKING block: "
+                + e.args[0]
+            ) from None
+
         for param in params.values():
             if param.annotation is Greedy:
                 msg = "Unparameterized Greedy[...] is disallowed in signature."

disnake/ext/commands/slash_core.py

@@ -306,7 +306,13 @@ def __init__(
         )
 
         if options is None:
-            options = expand_params(self)
+            try:
+                options = expand_params(self)
+            except NameError as e:
+                raise NameError(
+                    "Could not expand parameters. Please check all annotations are imported outside of TYPE_CHECKING blocks. "
+                    + e.args[0]
+                ) from None
 
         self.docstring = utils.parse_docstring(func)
         desc_loc = Localized._cast(description, False)
@@ -473,7 +479,13 @@ def __init__(
         )
 
         if options is None:
-            options = expand_params(self)
+            try:
+                options = expand_params(self)
+            except NameError as e:
+                raise NameError(
+                    "Could not expand parameter options. Please check all annotations are imported outside of TYPE_CHECKING blocks. "
+                    + e.args[0]
+                ) from None
 
         self.docstring = utils.parse_docstring(func)
         desc_loc = Localized._cast(description, False)