You're not covered for all types of errors, only single bit flips.
(I choose not to worry about flips of three bits or more. YMMV.)
This is dependent on the system configuration. For Linux, default behavior is to halt only if the uncorrected error occurs in memory used by the kernel.
It's more accurate to say that double bit flips will be detected.
Search for "edac_mc_panic_on_ue"