diff --git a/src/utils/index.ts b/src/utils/index.ts
index 0c36005..f300cad 100644
--- a/src/utils/index.ts
+++ b/src/utils/index.ts
@@ -52,6 +52,9 @@ export function setNested (obj: Record<string, any>, field: string, value: any):
                 subProxy = subProxy[matches[2]]
             }
         } else {
+            if (subProxy === undefined) {
+                break
+            }
             if (i === fieldParts.length - 1) {
                 subProxy[fieldPart] = value
                 break