Crash when calling toString on a NodeWrapper

[pdubroy]

file:///Users/pdubroy/dev/harc/ohm/packages/ohm-js/src/Semantics.js:41
    return '[semantics wrapper for ' + this._node.grammar.name + ']';
                                                          ^

TypeError: Cannot read properties of undefined (reading 'name')
    at Semantics.Wrapper.toString (file:///Users/pdubroy/dev/harc/ohm/packages/ohm-js/src/Semantics.js:41:59)
    at Semantics.Wrapper.Rule (file:///Users/pdubroy/dev/harc/ohm/packages/lang-python/convertToOhm.js:67:5)
    at Operation.execute (file:///Users/pdubroy/dev/harc/ohm/packages/ohm-js/src/Semantics.js:639:25)
    at Semantics.Wrapper.doIt [as rewrite] (file:///Users/pdubroy/dev/harc/ohm/packages/ohm-js/src/Semantics.js:373:29)
    at file:///Users/pdubroy/dev/harc/ohm/packages/lang-python/convertToOhm.js:63:62
    at Array.map (<anonymous>)
    at Semantics.Wrapper.Grammar (file:///Users/pdubroy/dev/harc/ohm/packages/lang-python/convertToOhm.js:63:51)
    at Operation.execute (file:///Users/pdubroy/dev/harc/ohm/packages/ohm-js/src/Semantics.js:639:25)
    at Semantics.Wrapper.doIt [as rewrite] (file:///Users/pdubroy/dev/harc/ohm/packages/ohm-js/src/Semantics.js:373:29)
    at file:///Users/pdubroy/dev/harc/ohm/packages/lang-python/convertToOhm.js:138:39