False positive test result

[Eternal-Rise]

All test cases matched as passed, but one of them failed with error.

> metacalc@0.0.2 test
> npm run lint && npm run types && metatests test/unit.js


> metacalc@0.0.2 lint
> eslint . && prettier -c "**/*.js" "**/*.json" "**/*.md" "**/.*rc" "**/*.ts"

Checking formatting...
All matched files use Prettier code style!

> metacalc@0.0.2 types
> tsc -p tsconfig.json

Node v16.16.0 (v8 9.4.146.24-node.21):
Simple expressions .................................... 3/3
Expression chain ...................................... 2/2
JavaScript Math ....................................... 8/8
Correct cell values ................................... 4/4
Non-table identifiers ................................. 3/3
Prevent arbitrary js code execution ................... 7/7
/home/eternal/dev/opensource/metarhia/metacalc/lib/sheet.js:18
      const targetProp = `${prop}.${currentProp}`;
                                    ^

TypeError: Cannot convert a Symbol value to a string
    at Object.get (/home/eternal/dev/opensource/metarhia/metacalc/lib/sheet.js:18:37)
    at Proxy.toString (<anonymous>)
    at Object.isError [as identify] (/home/eternal/dev/opensource/metarhia/metacalc/node_modules/metatests/lib/utils.js:45:50)
    at /home/eternal/dev/opensource/metarhia/metacalc/node_modules/yaml/dist/Schema-88e323a7.js:396:42
    at Array.find (<anonymous>)
    at findTagObject (/home/eternal/dev/opensource/metarhia/metacalc/node_modules/yaml/dist/Schema-88e323a7.js:396:15)
    at createNode (/home/eternal/dev/opensource/metarhia/metacalc/node_modules/yaml/dist/Schema-88e323a7.js:409:16)
    at Schema.createNode (/home/eternal/dev/opensource/metarhia/metacalc/node_modules/yaml/dist/Schema-88e323a7.js:507:12)
    at stringify (/home/eternal/dev/opensource/metarhia/metacalc/node_modules/yaml/dist/Document-9b4560a1.js:190:19)
    at Document.toString (/home/eternal/dev/opensource/metarhia/metacalc/node_modules/yaml/dist/Document-9b4560a1.js:737:20)

Reproducing: https://github.com/Eternal-Rise/metacalc/tree/false-positive-test