The stance row, and the second reader.

The reader is stance, in the table at src/Standing/Standing.lua:56, and every shapeshifting class uses it. It walks GetShapeshiftFormInfo and matches each slot's spell name against the bar rather than indexing into it, which is the correction to item 52's guess: GetShapeshiftForm answers a position on a bar holding only the forms you have learned. A slot matched and missing draws empty, the way an empty totem slot already does.

A stance fills three of the five reader values, and src/Standing/Row.lua:261 already reads the other two as expires[index] or 0 and span[index] or 0, so Row.lua does not change. GetShapeshiftFormInfo and GetNumShapeshiftForms are not in the harness; they go beside GetShapeshiftForm at scripts/harness/client/05-quests.lua:691, not in 03-player.lua.

The plan goes in src/Class/Warrior.lua beside forms: three slots in that file's order, kind = "stance", word = "stances", one = "stance".

src/Standing/Feature.lua:105 writes its slash words at file load, before the client will say what class this is, so every class's word lives in that table: forms, aspects, poisons, auras, demon. That is the one file outside Class/ a new class edits, and the fix is a gate: hold every word and one a plan registers against the table, and fail on a table word no plan claims.