Fix `sb3_contrib/common/utils.py` type hint (#120)

* Update contribution.md

* New loop struct to make mypy happy

* Update setup.cfg

* Update changelog

* Add return statement in cg solver for max_iter=0

Co-authored-by: Antonin Raffin <antonin.raffin@ensta.org>

CONTRIBUTING.md

@@ -152,7 +152,7 @@ To run tests with `pytest`:
 make pytest
 ```
 
-Type checking with `pytype`:
+Type checking with `pytype` and `mypy`:
 
 ```
 make type
@@ -165,7 +165,7 @@ make check-codestyle
 make lint
 ```
 
-To run `pytype`, `format` and `lint` in one command:
+To run `type`, `format` and `lint` in one command:
 ```
 make commit-checks
 ```

docs/misc/changelog.rst

@@ -27,6 +27,7 @@ Deprecations:
 Others:
 ^^^^^^^
 - Fixed flake8 config
+- Fixed ``sb3_contrib/common/utils.py`` type hint
 
 Release 1.6.2 (2022-10-10)
 --------------------------

sb3_contrib/common/utils.py

@@ -133,6 +133,8 @@ def conjugate_gradient_solver(
         beta = new_residual_squared_norm / residual_squared_norm
         residual_squared_norm = new_residual_squared_norm
         p = residual + beta * p
+    # Note: this return statement is only used when max_iter=0
+    return x
 
 
 def flat_grad(

setup.cfg

@@ -32,7 +32,6 @@ exclude = (?x)(
 	| sb3_contrib/common/recurrent/type_aliases.py$
 	| sb3_contrib/common/recurrent/policies.py$
 	| sb3_contrib/common/recurrent/buffers.py$
-	| sb3_contrib/common/utils.py$
 	| sb3_contrib/common/maskable/distributions.py$
 	| sb3_contrib/common/maskable/callbacks.py$
 	| sb3_contrib/common/maskable/policies.py$