BME680 suddenly died after a couple months, what do these error codes mean?

BME680 running BSEC 2.4.0.0 on a Particle Photon

Has been running fine for 2 months, then suddenly started reporting all values as 0. 

Debug lists "BSEC error code: -12" and "BME68x error code: -2", but the BST-BME-Integration-Guide-AN011-40.pdf does not list any numerical error codes, only text error strings which the included basic_config_state.ino does not display.

 

What do these error codes mean?

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