The CIL opcode table held five of the six ECMA-335 prefix opcodes and
omitted no. (FE 19 <unsigned int8>, III.2.2). A method body using it was
reported as malformed with "Unsupported CIL opcode 0xfe19", losing its
instruction counts and normalized IL digest.
Decode it with its one-byte check mask and treat it as a prefix, so it
shares an instruction boundary with the opcode it modifies.
Claude-Session: https://claude.ai/code/session_012pRGskbPGjT444CgJfuhhj
Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>