Fetches a single message over the specified receiver link.
async amqp.fetchMessage(linkName : string): Promise<void>
When FetchMessage is called, the class will supply the sender with a single credit and then block until a message is received (if the FetchTimeout property is set to zero).
If FetchTimeout is non-zero, the class will only block for the specified number of seconds; once that time expires, it will instruct the sender to consume the credit. If the sender chooses to consume the credit by incrementing the value of the LinkDeliveryCount property rather than by sending a message, then the class will throw an error indicating a timeout.
LinkName specifies the receiver link which should fetch a message; if there is no such link, if the specified link is not a receiver link, or if the specified receiver link is not operating in rmSyncGet (1) mode, an error is thrown.