Minor issue with zero connections

[wkitlasten]

I am getting a MF6 warning:

WARNING REPORT:

1. SFR Package SFR_0 has 3 reach(es) with zero connections.
   Normal termination of simulation.

It appears the ones in question have to_rno = 0 and from_rnos = {}. They don't seem to be causing an issue, but perhaps they should be dropped?

[wkitlasten]

Further digging suggests if rno = 1 does not have a downstream connection flopy fails while loading connection data (but strangely failed on line 17?). MF6 seems to run it okay:

sim=flopy.mf6.MFSimulation.load(sim_ws)
gwf=sim.get_model(my_model)

Full error report:

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
D:\modelling\flopy\flopy\mf6\data\mffileaccess.py in read_list_data_from_file(self, file_handle, storage, current_key, current_line, data_line, store_internal)
   1441                         current_key=current_key,
-> 1442                         data_line=data_line,
   1443                     )[1]

D:\modelling\flopy\flopy\mf6\data\mffileaccess.py in load_list_line(self, storage, arr_line, line_num, data_loaded, build_type_list, current_key, data_index_start, data_set, ignore_optional_vars, data_line, zero_based)
   1855                                         data_line,
-> 1856                                         zero_based=zero_based,
   1857                                     )

D:\modelling\flopy\flopy\mf6\data\mffileaccess.py in _append_data_list(self, storage, data_item, arr_line, arr_line_len, data_index, var_index, repeat_count, current_key, data_line, add_to_last_line, zero_based)
   2161                         data_item,
-> 2162                         sub_amt=sub_amt,
   2163                     )

D:\modelling\flopy\flopy\mf6\data\mfdatautil.py in convert_data(data, data_dimensions, data_type, data_item, sub_amt)
     87         if data_item is not None and data_item.numeric_index:
---> 88             return int(PyListUtil.clean_numeric(data)) - sub_amt
     89         try:

ValueError: invalid literal for int() with base 10: '17    -18'

During handling of the above exception, another exception occurred:

MFDataException                           Traceback (most recent call last)
D:\modelling\flopy\flopy\mf6\mfpackage.py in load(self, block_header, fd, strict)
    860                         initial_comment,
--> 861                         external_file_info,
    862                     )

D:\modelling\flopy\flopy\mf6\data\mfdatalist.py in load(self, first_line, file_handle, block_header, pre_data_comments, external_file_info)
   1219         result = file_access.load_from_package(
-> 1220             first_line, file_handle, storage, pre_data_comments
   1221         )

D:\modelling\flopy\flopy\mf6\data\mffileaccess.py in load_from_package(self, first_line, file_handle, storage, pre_data_comments)
   1129                 current_line,
-> 1130                 self._data_line,
   1131             )

D:\modelling\flopy\flopy\mf6\data\mffileaccess.py in read_list_data_from_file(self, file_handle, storage, current_key, current_line, data_line, store_internal)
   1461                         self._simulation_data.debug,
-> 1462                         ex,
   1463                     )

MFDataException: An error occurred in data element "connectiondata" model "gwf6" package "sfr". The error occurred while loading data list from package file in the "read_list_data_from_file" method.
Additional Information:
(1) Unable to process line 17 of data list: "   17    -18
"


During handling of the above exception, another exception occurred:

MFDataException                           Traceback (most recent call last)
~\AppData\Local\Temp/ipykernel_22764/3270168176.py in <module>
      2 sim_ws=os.path.join('..','zmodels','20210717_simulation',model_name)
      3 model_ws=sim_ws
----> 4 sim=flopy.mf6.MFSimulation.load(sim_ws=sim_ws)
      5 gwf=sim.get_model(model_name)
      6 gwf.model_name=model_name

D:\modelling\flopy\flopy\mf6\modflow\mfsimulation.py in load(cls, sim_name, version, exe_name, sim_ws, strict, verbosity_level, load_only, verify_data, write_headers)
    680                 strict,
    681                 path,
--> 682                 load_only,
    683             )
    684 

D:\modelling\flopy\flopy\mf6\modflow\mfgwf.py in load(cls, simulation, structure, modelname, model_nam_file, version, exe_name, strict, model_rel_path, load_only)
    135             strict,
    136             model_rel_path,
--> 137             load_only,
    138         )

D:\modelling\flopy\flopy\mf6\mfmodel.py in load_base(cls, simulation, structure, modelname, model_nam_file, mtype, version, exe_name, strict, model_rel_path, load_only)
    799                     print("    loading package {}...".format(ftype))
    800                 # load package
--> 801                 instance.load_package(ftype, fname, pname, strict, None)
    802 
    803         # load referenced packages

D:\modelling\flopy\flopy\mf6\mfmodel.py in load_package(self, ftype, fname, pname, strict, ref_path, dict_package_name, parent_package)
   1406         )
   1407         try:
-> 1408             package.load(strict)
   1409         except ReadAsArraysException:
   1410             #  create ReadAsArrays package and load it instead

D:\modelling\flopy\flopy\mf6\mfpackage.py in load(self, strict)
   2040 
   2041         try:
-> 2042             self._load_blocks(fd_input_file, strict)
   2043         except ReadAsArraysException as err:
   2044             fd_input_file.close()

D:\modelling\flopy\flopy\mf6\mfpackage.py in _load_blocks(self, fd_input_file, strict, max_blocks)
   2226 
   2227                         cur_block.load(
-> 2228                             block_header_info, fd_input_file, strict
   2229                         )
   2230 

D:\modelling\flopy\flopy\mf6\mfpackage.py in load(self, block_header, fd, strict)
    871                             dataset.structure.name,
    872                             self.structure.name,
--> 873                             fd_block.name,
    874                         ),
    875                     )

MFDataException: An error occurred in data element "connectiondata" model "wairau_240_7" package "sfr_0". The error occurred while loading data list from package file in the "read_list_data_from_file" method.
Additional Information:
(1) Unable to process line 17 of data list: "   17    -18
"
(2) Error occurred while loading data "connectiondata" in block "connectiondata" from file "D:\modelling\zmodels\20210717_simulation\wairau_240_7\wairau_240_7.sfr.connection.dat".