fix nested connection implicit delete

Author: alixander

ci/release/changelogs/next.md

@@ -4,4 +4,5 @@
 
 #### Bugfixes ⛑️
 
+- Fixes `null` being set on a nested shape not working in certain cases when connections also pointed to that shape [1830](https://github.com/terrastruct/d2/pull/1830)
 - Fixes edge case of bad import syntax crashing using d2 as a library [1829](https://github.com/terrastruct/d2/pull/1829)

d2compiler/compile_test.go

@@ -3239,6 +3239,17 @@ y: null
 					assert.Equal(t, 0, len(g.Edges))
 				},
 			},
+			{
+				name: "delete-nested-connection",
+				run: func(t *testing.T) {
+					g, _ := assertCompile(t, `
+a -> b.c
+b.c: null
+`, "")
+					assert.Equal(t, 2, len(g.Objects))
+					assert.Equal(t, 0, len(g.Edges))
+				},
+			},
 			{
 				name: "delete-multiple-connections",
 				run: func(t *testing.T) {

d2ir/d2ir.go

@@ -950,13 +950,20 @@ func (m *Map) DeleteField(ida ...string) *Field {
 		}
 		if len(rest) == 0 {
 			for _, fr := range f.References {
-				for _, e := range m.Edges {
-					for _, er := range e.References {
-						if er.Context_ == fr.Context_ {
-							m.DeleteEdge(e.ID)
-							break
+				currM := m
+				for currM != nil {
+					for _, e := range currM.Edges {
+						for _, er := range e.References {
+							if er.Context_ == fr.Context_ {
+								currM.DeleteEdge(e.ID)
+								break
+							}
 						}
 					}
+					if NodeBoardKind(currM) != "" {
+						break
+					}
+					currM = ParentMap(currM)
 				}
 			}
 			m.Fields = append(m.Fields[:i], m.Fields[i+1:]...)