Tolerant edge cases in LosslessJsonParser

[ryanelee]

When there is a edge case in the input variable payload such as array of null elements, the recursive method convertLosslessNumbersToNumberOrThrow underneath the createWorker throws cannot read properties of null error.

SDK Component

Zeebe gRPC client

Expected Behavior

The null should be ignored and the JSON string should be serialized successfully

Current Behavior

The convertLosslessNumbersToNumberOrThrow method in LosslessJsonParser.ts throws out exception on the 1st line
debug(Parsing LosslessNumbers to numbers for ${obj.constructor.name}) when the obj is null.

Error:
Cannot read properties of null (reading 'constructor')

Possible Solution

Add the null check in the convertLosslessNumbersToNumberOrThrow method in LosslessJsonParser.ts.

Add safe navigation operation on line 223:
obj?.constructor?.name

Add a null check before 224:
if (!obj) return obj;

Steps to Reproduce

1. Added a new unit test in LosslessJsonParser.unit.spec.ts

test('LosslessJsonParser correctly handles null objects', () => {
    const json = `{"abc": [null, null, null] }`;

    const parsedDto = losslessParse(json);

    expect(parsedDto.siuTaskComments).toMatchObject([null, null, null]); // 3 (string)
});

2. Run the unit test
3. The new added unit test will be failed with below error:

An unsafe number value was received for "abc" and no Dto mapping was specified.
    Cannot read properties of null (reading 'constructor')

      248 |     } catch (e) {
      249 |             const message = (e as Error).message
    > 250 |             throw new Error(
          |                   ^
      251 |                     `An unsafe number value was received for "${currentKey}" and no Dto mapping was specified.\n` +
      252 |                             message
      253 |             )

Context (Environment)

The error will stop Zeebe gRPC client from polling activate tasks.

[jwulf]

Thanks for finding this and suggesting a fix. I've implemented it.