Failed to build variable mapping expression

[remcowesterhoud]

Describe the bug
I deploy a a process with a specific output variable mapping. Instead of breaking on the validation, the broker throws an exception and the deployment fails.

To Reproduce

Deploy this process using Zeebe 1.2

<?xml version="1.0" encoding="UTF-8"?>
<bpmn:definitions xmlns:bpmn="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" xmlns:zeebe="http://camunda.org/schema/zeebe/1.0" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" xmlns:modeler="http://camunda.org/schema/modeler/1.0" id="Definitions_1l8zqol" targetNamespace="http://bpmn.io/schema/bpmn" exporter="Camunda Modeler" exporterVersion="4.11.0" modeler:executionPlatform="Camunda Cloud" modeler:executionPlatformVersion="1.1.0">
  <bpmn:process id="Process_00dmwud" isExecutable="true">
    <bpmn:startEvent id="StartEvent_1">
      <bpmn:outgoing>Flow_0b71pnj</bpmn:outgoing>
    </bpmn:startEvent>
    <bpmn:endEvent id="Event_12llkjs">
      <bpmn:incoming>Flow_0hl1ts4</bpmn:incoming>
    </bpmn:endEvent>
    <bpmn:sequenceFlow id="Flow_0b71pnj" sourceRef="StartEvent_1" targetRef="Activity_13r0dql" />
    <bpmn:sequenceFlow id="Flow_0hl1ts4" sourceRef="Activity_13r0dql" targetRef="Event_12llkjs" />
    <bpmn:serviceTask id="Activity_13r0dql">
      <bpmn:extensionElements>
        <zeebe:taskDefinition type="type" retries="1" />
        <zeebe:ioMapping>
          <zeebe:output source="= result.CheckProcess.generalClassifications.operational[type=&#34;ACCOUNTING_PERIOD_VALIDATION&#34;][1]" target="accountingPeriodValidation.operational" />
          <zeebe:output source="= result.CheckProcess.generalClassifications.heating[type=&#34;ACCOUNTING_PERIOD_VALIDATION&#34;][1]" target="accountingPeriodValidation.heating" />
          <zeebe:output source="= result.CheckProcess.tenancy.utilityBill.operational" target="formalRequirementValidation.operational" />
          <zeebe:output source="= result.CheckProcess.tenancy.utilityBill.heating" target="formalRequirementValidation.heating" />
        </zeebe:ioMapping>
      </bpmn:extensionElements>
      <bpmn:incoming>Flow_0b71pnj</bpmn:incoming>
      <bpmn:outgoing>Flow_0hl1ts4</bpmn:outgoing>
    </bpmn:serviceTask>
  </bpmn:process>
  <bpmndi:BPMNDiagram id="BPMNDiagram_1">
    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="Process_00dmwud">
      <bpmndi:BPMNEdge id="Flow_0hl1ts4_di" bpmnElement="Flow_0hl1ts4">
        <di:waypoint x="360" y="117" />
        <di:waypoint x="412" y="117" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_0b71pnj_di" bpmnElement="Flow_0b71pnj">
        <di:waypoint x="215" y="117" />
        <di:waypoint x="260" y="117" />
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNShape id="_BPMNShape_StartEvent_2" bpmnElement="StartEvent_1">
        <dc:Bounds x="179" y="99" width="36" height="36" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_12llkjs_di" bpmnElement="Event_12llkjs">
        <dc:Bounds x="412" y="99" width="36" height="36" />
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Activity_0s27z46_di" bpmnElement="Activity_13r0dql">
        <dc:Bounds x="260" y="77" width="100" height="80" />
      </bpmndi:BPMNShape>
    </bpmndi:BPMNPlane>
  </bpmndi:BPMNDiagram>
</bpmn:definitions>

The process above contains the original output variable mappings. I've pinpointed it down a bit.
Expression = x.y[z = 0][1] causes this issue. = x[z = 0][1] works without a problem. = x.y[z = 0] also works without issue.

Expected behavior
I think the expression is a valid expression. If it is, the deployment should succeed. If it is not I would expect the broker to fail on a validation instead of throwing an exception.

Environment

• FEEL engine version: [1.13.3]
• Affects:
  • Zeebe broker: [1.2.1] IllegalStateException: Failed to build variable mapping expression camunda#8066

[saig0]

I can reproduce the bug with the following expression:

 {z: x.y[1][1]}.z

> Failure(failed to parse expression ' {z: x.y[1][1]}.z ': Expected (expressionWithContinuation | functionDefinition | forExpression | ifExpression | quantifiedExpression | expression2):1:2, found "{z: x.y[1]")

The bug is already fixed in version 1.14.0. I added a new test case for this unary-tests expression with #377.