how to extract coefficient from a gamma distribution?

I'm trying to fit the gamma probability distribution to time series datasets suing the following command gam<-fitdistr(x=hist2fit,"gamma") where hist2fit is the bar histogram of a sample distribution.

The problem is that for some points, it is not possible to fit the gamma distribution for instance with an histogram having identical value.

I would like to know how to test whether the command gam<-fitdistr(x=hist2fit,"gamma") properly ended such that I can decide to save the gamma-parameters (for instance as NaN  in this case).

Without this test, the program stops when I try to store the scale and the shape parameters.

Any thoughts for a code will be very much appreciated.