handle error when you try and download file too many times

[rabutler-usbr]

If you try and download a file too many times you receive the following error txt file:

PRISM_tdmean_stable_4kmM3_1970_all_bil_error_msg_10.txt

[rabutler-usbr]

RCurl::getURLContent(uri2) returns "application/zip" for a file that can be downloaded and "application/octet-stream" for the text file error message.

However, it uses up 1 of the downloads for the day. Ex: calling it three times will result in the third call returning the error text.

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One idea - download as is normally done. If after unzipping the folder, the folder is empty, try renaming the zip folder to .txt, and then try scanning it as a text file. If you get expected text then print the message and delete the folder and zip file.

[rabutler-usbr]

Implemented by using readLines() and checking to see if is PK\003\004, which indicates it's a zip. Otherwise posts warning and returns text that was read in.