Apply suggestions from code review

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: henryiii

docs/advanced/pycpp/numpy.rst

@@ -261,7 +261,7 @@ them mapping to respective C++ counterparts.
 
 .. note::
 
-    This is a strict type, it will only allows to specify NumPy type as input
+    This is a strict type, it will only allow to specify NumPy type as input
     arguments, and does not allow other types of input parameters (e.g.,
     ``py::numpy_scalar<int64_t>`` will not accept Python's builtin ``int`` ).
 

include/pybind11/numpy.h

@@ -811,7 +811,7 @@ struct numpy_scalar {
     numpy_scalar() = default;
     explicit numpy_scalar(value_type value) : value(value) {}
 
-    explicit operator value_type() { return value; }
+    explicit operator value_type() const { return value; }
     numpy_scalar &operator=(value_type value) {
         this->value = value;
         return *this;