Update error handling for os2 on windows

core/os/os2/errors_windows.odin

@@ -12,3 +12,49 @@ _error_string :: proc(errno: i32) -> string {
 	// FormatMessageW
 	return ""
 }
+
+_get_platform_error :: proc() -> Error {
+	err := win32.GetLastError()
+	if err == 0 {
+		return nil
+	}
+	switch err {
+	case win32.ERROR_ACCESS_DENIED, win32.ERROR_SHARING_VIOLATION:
+		return .Permission_Denied
+
+	case win32.ERROR_FILE_EXISTS, win32.ERROR_ALREADY_EXISTS:
+		return .Exist
+
+	case win32.ERROR_FILE_NOT_FOUND, win32.ERROR_PATH_NOT_FOUND:
+		return .Not_Exist
+
+	case win32.ERROR_NO_DATA:
+		return .Closed
+
+	case win32.ERROR_TIMEOUT, win32.WAIT_TIMEOUT:
+		return .Timeout
+
+	case win32.ERROR_NOT_SUPPORTED:
+		return .Unsupported
+
+	case
+		win32.ERROR_BAD_ARGUMENTS,
+		win32.ERROR_INVALID_PARAMETER,
+		win32.ERROR_NOT_ENOUGH_MEMORY,
+		win32.ERROR_INVALID_HANDLE,
+		win32.ERROR_NO_MORE_FILES,
+		win32.ERROR_LOCK_VIOLATION,
+		win32.ERROR_HANDLE_EOF,
+		win32.ERROR_BROKEN_PIPE,
+		win32.ERROR_CALL_NOT_IMPLEMENTED,
+		win32.ERROR_INSUFFICIENT_BUFFER,
+		win32.ERROR_INVALID_NAME,
+		win32.ERROR_LOCK_FAILED,
+		win32.ERROR_ENVVAR_NOT_FOUND,
+		win32.ERROR_OPERATION_ABORTED,
+		win32.ERROR_IO_PENDING,
+		win32.ERROR_NO_UNICODE_TRANSLATION:
+		// fallthrough
+	}
+	return Platform_Error(err)
+}