A warning not suppressed

The flag -w does not seem to suppress all warnings (example taken from the use case):

$ texts session -r -a -u 87c94d1730c24feb9789b7747f9c2d0e -w
Resource configuration /home/kit/scc/jk7683/.fireworks/res_config.yaml exists.
Warning: None:5:188 --> Reaction MOOH + 0.5 H2 = MO + H2O <--
reaction balance check skipped due to missing composition in some terms
Warning: None:10:37 --> Reaction M + O2 + 0.5 H2 = MOOH <--
reaction balance check skipped due to missing composition in some terms
Warning: None:28:10 --> Reaction MOH + 0.5 H2 = M + H2O <--
reaction balance check skipped due to missing composition in some terms
Warning: None:156:90 --> Reaction MO + 0.5 H2 = MOH <--
reaction balance check skipped due to missing composition in some terms
Welcome to textS/textM. Type %help for some help.