improve error messages

src/write_coeff.cpp

@@ -41,7 +41,7 @@ void WriteCoeff::command(int narg, char **arg)
   if (domain->box_exist == 0)
     error->all(FLERR, "Write_coeff command before simulation box is defined");
 
-  if (narg != 1) error->all(FLERR, "Illegal write_coeff command");
+  if (narg != 1) utils::missing_cmd_args(FLERR, "write_coeff", error);
 
   char *file = utils::strdup(fmt::format("{}.tmp", arg[0]));
 
@@ -167,6 +167,5 @@ void WriteCoeff::command(int narg, char **arg)
     fclose(two);
     platform::unlink(file);
   }
-
   delete[] file;
 }