src.csv table not populating COMID numbers for all stream segments

[mdp0023]

Running a catchment in Austin (happens a few times in a few different catchments) where the src table doesn't populate the COMID value for some of the channel segments. Looks like it is a smaller channel segment (less than 100 meters in length). Causing inundation function to crash. Attached are some of the relevant files showing missing COMID value.

dem_5781307_201310310900_floodstage.csv
dem_5781307_river_attributes.csv
dem_5781307_src.csv

[mdp0023]

Two potential patches in tools.py:

1. in get_flood_stage, skip over when comid is nan. Does not map inundation for this reach segement. Potential error in missing inundation extent
2. in get_river_attributes, add additional sjoin based on nearest catchment. Fills gaps, allows for inundation to be mapped for missing reach segements. Potential error based on HAND, where inundation depth is exceedingly high. Might be related to d8 flow direction in HAND calculation

testing patches in src_patch branch