add sanity check for number of contrasts user specifies

sanity_check_inputs/sanity_check_config_metadata.Rmd

@@ -277,6 +277,13 @@ if (config$excerpt_merged_results_dir != "none" & base::file.exists(base::file.p
   issues_config <- c(issues_config, base::paste0("Unable to find the excerpt gencode count datasets to be analysed based on the directory passed to 'excerpt_results_dir' in the configuration file. The following path was passed: ",
                                                  base::file.path(config$excerpt_merged_results_dir, "exceRpt_gencode_ReadCounts.txt")))
   
+}
+
+# check the number of contrasts (treatment comparisons) the user has chosen is between 1 and 10 contrasts
+if (base::length(config$contrasts) > 10) {
+  
+  issues_config <- c(issues_config, base::paste0("It appears that you have many contrasts (treatment comparisons) for the differential expression analysis based on 'contrasts' in the configuration file. Please ensure there are 10 or fewer contrasts"))
+  
 }
 ```