ld-analyse crash when selecting reload TBC option

[simoninns]

Started decoding a copy of natA domesday - after ld-decode was running for about 50-60 frames I opened the TBC in ld-analyse then, a little later, clicked the reload TBC option and got a crash:

ld-analyse DS2_natA_PP.tbc
Critical: JSON file invalid: numberOfSequentialFields does not match fields array
Warning: Open TBC JSON metadata failed for filename "DS2_natA_PP.tbc"
Critical: Comb::Comb(): Frame width exceeds allowed maximum!
Critical: Comb::Comb(): Frame height exceeds allowed maximum!
Critical: LdDecodeMetaData::getFieldNumber(): Both of the determined fields have isFirstField set - the TBC source video is probably broken...
Critical: LdDecodeMetaData::getFieldNumber(): Both of the determined fields have isFirstField set - the TBC source video is probably broken...
Critical: Attempting to get field number failed - no isFirstField in JSON before end of file
Critical: LdDecodeMetaData::getField(): Requested field number -1 out of bounds!
Critical: LdDecodeMetaData::getFieldNumber(): Both of the determined fields have isFirstField set - the TBC source video is probably broken...
Critical: LdDecodeMetaData::getField(): Requested field number -1 out of bounds!
Critical: Attempting to get field number failed - no isFirstField in JSON before end of file
Critical: LdDecodeMetaData::getField(): Requested field number -1 out of bounds!
Critical: LdDecodeMetaData::getFieldNumber(): Both of the determined fields have isFirstField set - the TBC source video is probably broken...
Critical: LdDecodeMetaData::getField(): Requested field number -1 out of bounds!
Segmentation fault (core dumped)

Looks like this is related to pull #721 ?