Add InvalidArgumentsError

* Avoid confusion with random type errors in methods.

jsonrpcserver/dispatcher.py

@@ -36,6 +36,7 @@
 )
 from .errors import (
     MethodNotFoundError,
+    InvalidArgumentsError,
     ApiError,
 )
 
@@ -131,9 +132,9 @@ def handle_exceptions(request: Request, debug: bool) -> Generator:
         handler.response = MethodNotFoundResponse(
             id=request.id, data=request.method, debug=debug
         )
-    except (TypeError, AssertionError) as exc:
-        # Invalid Params - TypeError is raised by jsonschema, AssertionError raised
-        # inside the methods.
+    except (InvalidArgumentsError, AssertionError) as exc:
+        # Invalid Params - InvalidArgumentsError is raised by validate_args,
+        # AssertionError raised inside the methods.
         handler.response = InvalidParamsResponse(
             id=request.id, data=str(exc), debug=debug
         )

jsonrpcserver/errors.py

@@ -8,6 +8,10 @@ class MethodNotFoundError(KeyError):
     """ Method lookup failed """
     pass
 
+class InvalidArgumentsError(TypeError):
+    """ Method arguments invalid """
+    pass
+
 class ApiError(RuntimeError):
     """ A method responds with a custom error """
 

jsonrpcserver/methods.py

@@ -10,7 +10,7 @@
 
 from inspect import signature
 
-from .errors import MethodNotFoundError
+from .errors import MethodNotFoundError, InvalidArgumentsError
 
 Method = Callable[..., Any]
 
@@ -27,9 +27,12 @@ def validate_args(func: Method, *args: Any, **kwargs: Any) -> Method:
         kwargs: Keyword arguments.
 
     Raises:
-        TypeError: If the arguments cannot be passed to the function.
+        InvalidArgumentsError: If the arguments cannot be passed to the function.
     """
-    signature(func).bind(*args, **kwargs)
+    try:
+        signature(func).bind(*args, **kwargs)
+    except TypeError as exc:
+        raise InvalidArgumentsError from exc
     return func