running ` devtools::install_github('dkahle/ggmap')` causing `Error in `*tmp*`[[c(1, 1)]] : subscript out of bounds`

Hey,

I ran` devtools::install_github('dkahle/ggmap')` when trying to fix the issue of ggmap mapdist function repeating calculation for certain O-D pairs.

before running this the code `mapdist('Manchester Deaf Institute', 'Birmingham O2 Academy 1', mode = 'driving')` would return a result, however now after running ` devtools::install_github('dkahle/ggmap')`
I just get the following error `Error in `*tmp*`[[c(1, 1)]] : subscript out of bounds`

I am no where near the API limit for the day, and as this was working perfectly beforehand I am unsure why this is not working ( I am not sure it this is similar to this issue https://github.com/dkahle/ggmap/issues/166)

Is this a known issue?

thanks