fix(drilldown): handle missing process (parent) DI elements

lib/features/drilldown/DrilldownBreadcrumbs.js

@@ -62,29 +62,36 @@ export default function DrilldownBreadcrumbs(eventBus, elementRegistry, canvas)
     }
 
     var path = businessObjectParents.map(function(parent) {
-      var title = escapeHTML(parent.name || parent.id);
-      var link = domify('<li><span class="bjs-crumb"><a title="' + title + '">' + title + '</a></span></li>');
-
-      var parentPlane = canvas.findRoot(getPlaneIdFromShape(parent)) || canvas.findRoot(parent.id);
+      var parentPlane =
+        canvas.findRoot(getPlaneIdFromShape(parent)) ||
+        canvas.findRoot(parent.id);
 
-      // when the root is a collaboration, the process does not have a corresponding
-      // element in the elementRegisty. Instead, we search for the corresponding participant
+      // when the root is a collaboration, the process does not have a
+      // corresponding element in the elementRegisty. Instead, we search
+      // for the corresponding participant
       if (!parentPlane && is(parent, 'bpmn:Process')) {
         var participant = elementRegistry.find(function(element) {
           var businessObject = getBusinessObject(element);
 
-          return businessObject && businessObject.get('processRef') && businessObject.get('processRef') === parent;
+          return businessObject && businessObject.get('processRef') === parent;
         });
 
-        parentPlane = canvas.findRoot(participant.id);
+        parentPlane = participant && canvas.findRoot(participant.id);
+      }
+
+      if (!parentPlane) {
+        return null;
       }
 
+      var title = escapeHTML(parent.name || parent.id);
+      var link = domify('<li><span class="bjs-crumb"><a title="' + title + '">' + title + '</a></span></li>');
+
       link.addEventListener('click', function() {
         canvas.setRootElement(parentPlane);
       });
 
       return link;
-    });
+    }).filter(link => link);
 
     breadcrumbs.innerHTML = '';
 

test/spec/features/drilldown/DrilldownSpec.js

@@ -625,6 +625,18 @@ describe('features/drilldown - integration', function() {
       expect(warnings).to.be.empty;
     });
 
+
+    it('no <bpmndi:BPMNDiagram /> for process', async function() {
+
+      const {
+        error,
+        warnings
+      } = await importXML(processMissingBpmnDiagram_XML);
+
+      // then
+      expect(error).not.to.exist;
+      expect(warnings).to.be.empty;
+    });
   });
 
 });

test/spec/features/drilldown/process-missing-bpmndiagram.bpmn

@@ -0,0 +1,15 @@
+<?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:modeler="http://camunda.org/schema/modeler/1.0" id="DEFINITIONS" targetNamespace="http://bpmn.io/schema/bpmn" exporter="Camunda Modeler" exporterVersion="5.12.0" modeler:executionPlatform="Camunda Platform" modeler:executionPlatformVersion="7.19.0">
+  <bpmn:process id="PROCESS" isExecutable="true">
+    <bpmn:subProcess id="SUB_PROCESS_PLANE">
+      <bpmn:task id="TASK_IN_SUBPROCESS" name="TASK_IN_SUBPROCESS" />
+    </bpmn:subProcess>
+  </bpmn:process>
+  <bpmndi:BPMNDiagram id="BPMNDiagram_1">
+    <bpmndi:BPMNPlane id="BPMNPlane_2" bpmnElement="SUB_PROCESS_PLANE">
+      <bpmndi:BPMNShape id="TASK_IN_SUBPROCESS_di" bpmnElement="TASK_IN_SUBPROCESS" isExpanded="false">
+        <dc:Bounds x="160" y="90" width="100" height="80" />
+      </bpmndi:BPMNShape>
+    </bpmndi:BPMNPlane>
+  </bpmndi:BPMNDiagram>
+</bpmn:definitions>