Lines 1542-1543: "... or for the value to be sent to zero, or to be set greater than 2,684,354,565."

Rewrite: "or for the value to be set to zero or greater than 2,684,354,565."

Also -

Line 1544 - "The packet size is the total number of bytes in an MQTT Control Packet, as defined in section 2.1.4. "

Section 2.1.4 is Remaining Length rather than the entire size of the packet.