Fix '0' being interpreted as a count prefix instead of a command

src/core/CommandMap.cc

@@ -72,7 +72,9 @@ uint8_t CommandMap::scan_units(
     for (size_t i = 0u; i < length; i++)
     {
         uint32_t c = command_characters[i];
-        if (gathering_count && ('0' <= c) && (c <= '9'))
+        if (gathering_count &&
+                ((('1' <= c) && (c <= '9')) ||
+                 ((c == '0') && (unit.count != 0u))))
         {
             unit.count *= 10u;
             unit.count += (c - '0');