use-of-uninitialized-value in Mat VarReadNumeric5

use-of-uninitialized-value in Mat VarReadNumeric5: a task in MiMo-V2.6-RL-oss: Agentic RL Environments (MiMo RL release). MemorySanitizer: use-of-uninitialized-value in function Mat VarReadNumeric5 in file matio/src/mat5.c