HAL4RT — Inconsistent definition of notify_error(), and return value of "notify_error()" seems not necessary

The definition of notify_error() functions in "ApplicationBase" and "System" are inconsistent.

p.19, 7.4.3.1, Table 7.4
notify_error()'s return type is not defined explicitly, but definition of class and interface table in 7.2 describes as follows: "Also, as the type of return code for every operation in this specification is Returncode, which is defined in Section7.3, Return Codes, this is omitted in the description table." Therefore, return type of the notify_error() is ReturnCode from the definition in the table.

p.19, 7.4.3, Figure 7.6
ApplicationBase::notify_error() and System::notify_error() in the figure are defined as having no return value.

p.21, 7.4.3.2, Table 7.7
Return type of the notify_error() is ReturnCode from the definition in the table.

p.33, 7.5.2 C PSM
ApplicationBase::notify_error(), Event::notify_error() are defined as having int32_t type return value.

Since the notify_error() functions are just callback functions, return value of "notify_error" seems not necessary.