Text format log input results in blank display with no error message

The text format looks like this:
```
FMT, 128, 89, FMT, BBnNZ, Type,Length,Name,Format,Columns
FMT, 219, 76, UNIT, QbZ, TimeUS,Id,Label
FMT, 218, 44, FMTU, QBNN, TimeUS,FmtType,UnitIds,MultIds
FMT, 220, 20, MULT, Qbd, TimeUS,Id,Mult
FMT, 129, 31, PARM, QNf, TimeUS,Name,Value
FMT, 130, 50, GPS, QBIHBcLLeffffB, TimeUS,Status,GMS,GWk,NSats,HDop,Lat,Lng,Alt,Spd,GCrs,VZ,Yaw,U
```

Reproduce the blank display in the online viewer using the supplied text-format log sample, then trace the input-handling entry point that processes this format. Done means the sample is displayed correctly or a clear error message is shown instead of a blank view.

Written by the indexing model from the issue text.