updated for version 7.4.145

Problem:    getregtype() does not return zero for unknown register.
Solution:   Adjust documention: return empty string for unknown register.
            Check the register name to be valid. (Yukihiro Nakadaira)

src/ops.c

@@ -6240,7 +6240,9 @@ get_reg_type(regname, reglen)
     regname = may_get_selection(regname);
 #endif
 
-    /* Should we check for a valid name? */
+    if (regname != NUL && !valid_yank_reg(regname, FALSE))
+        return MAUTO;
+
     get_yank_register(regname, FALSE);
 
     if (y_current->y_array != NULL)