Work around strange cast/type checking issue

For some reason, line 421 (the responds to call check) excluded the stub's call type.
Luckily this line doesn't seem to be necessary anymore.
Removed the unecessary quick check.

The tests from spec/spectator/mocks/double_spec:88-96 were failing when they're the only tests in the file.
The non-matching stub wouldn't raise.
Stepping through, attempting to access the value would segfault.
This is because it accessed a stub with String instead of its real Int32 type.
Removing the aforementioned check fixes this.

src/spectator/mocks/stubbable.cr

@@ -398,7 +398,7 @@ module Spectator
       {% end %}
     end
 
-    # Utility macro for casting a stub (and it's return value) to the correct type.
+    # Utility macro for casting a stub (and its return value) to the correct type.
     #
     # *stub* is the variable holding the stub.
     # *call* is the variable holding the captured method call.
@@ -408,49 +408,37 @@ module Spectator
     # - `:raise` - raise a `TypeCastError`.
     # - `:no_return` - raise as no value should be returned.
     private macro _spectator_cast_stub_value(stub, call, type, fail_cast = :nil)
-      # Attempt to cast the stub to the method's return type.
-      # If successful, return the value of the stub.
-      # This is a common usage where the return type is simple and matches the stub type exactly.
-      if %typed = {{stub}}.as?(::Spectator::TypedStub({{type}}))
-        %typed.call({{call}})
-      else
-        # The stub couldn't be easily cast to match the return type.
+      {% if fail_cast == :no_return %}
+        {{stub}}.call({{call}})
+        raise TypeCastError.new("#{_spectator_stubbed_name} received message #{ {{call}} } and is attempting to return a value, but it shouldn't have returned (`NoReturn`).")
+      {% else %}
+        # Get the value as-is from the stub.
+        # This will be compiled as a union of all known stubbed value types.
+        %value = {{stub}}.call({{call}})
 
-        # Even though all stubs will have a `#call` method, the compiler doesn't seem to agree.
-        # Assert that it will (this should never fail).
-        raise TypeCastError.new("Stub has no value") unless {{stub}}.responds_to?(:call)
-
-        {% if fail_cast == :no_return %}
-          {{stub}}.call({{call}})
-          raise TypeCastError.new("#{_spectator_stubbed_name} received message #{ {{call}} } and is attempting to return a value, but it shouldn't have returned (`NoReturn`).")
-        {% else %}
-          # Get the value as-is from the stub.
-          # This will be compiled as a union of all known stubbed value types.
-          %value = {{stub}}.call({{call}})
-
-          # Attempt to cast the value to the method's return type.
-          # If successful, which it will be in most cases, return it.
-          # The caller will receive a properly typed value without unions or other side-effects.
-          if %cast = %value.as?({{type}})
-            %cast
-          else
-            {% if fail_cast == :nil %}
-              nil
-            {% elsif fail_cast == :raise %}
-              # The stubbed value was something else entirely and cannot be cast to the return type.
-              # There's something weird going on (compiler bug?) that sometimes causes this class lookup to fail.
-              %type = begin
-                %value.class.to_s
-              rescue
-                "<Unknown>"
-              end
-              raise TypeCastError.new("#{_spectator_stubbed_name} received message #{ {{call}} } and is attempting to return a `#{%type}`, but returned type must be `#{ {{type}} }`.")
-            {% else %}
-              {% raise "fail_cast must be :nil, :raise, or :no_return, but got: #{fail_cast}" %}
-            {% end %}
-          end
-        {% end %}
-      end
+        # Attempt to cast the value to the method's return type.
+        # If successful, which it will be in most cases, return it.
+        # The caller will receive a properly typed value without unions or other side-effects.
+        %cast = %value.as?({{type}})
+        if %cast.is_a?({{type}})
+          %cast
+        else
+          {% if fail_cast == :nil %}
+            nil
+          {% elsif fail_cast == :raise %}
+            # The stubbed value was something else entirely and cannot be cast to the return type.
+            # There's something weird going on (compiler bug?) that sometimes causes this class lookup to fail.
+            %type = begin
+              %value.class.to_s
+            rescue
+              "<Unknown>"
+            end
+            raise TypeCastError.new("#{_spectator_stubbed_name} received message #{ {{call}} } and is attempting to return a `#{%type}`, but returned type must be `#{ {{type}} }`.")
+          {% else %}
+            {% raise "fail_cast must be :nil, :raise, or :no_return, but got: #{fail_cast}" %}
+          {% end %}
+        end
+      {% end %}
     end
   end
 end