fix(compiler-sfc): add error handling for defineModel() without variable assignment

packages/compiler-sfc/__tests__/compileScript.spec.ts

@@ -980,7 +980,7 @@ describe('SFC compile <script setup>', () => {
       expect(() =>
         compile(`<script setup>
         let bar = 1
-        defineModel({
+        const model = defineModel({
           default: () => bar
         })
         </script>`),
@@ -990,7 +990,7 @@ describe('SFC compile <script setup>', () => {
       expect(() =>
         compile(`<script setup>
         const bar = 1
-        defineModel({
+        const model = defineModel({
           default: () => bar
         })
         </script>`),
@@ -1000,7 +1000,7 @@ describe('SFC compile <script setup>', () => {
       expect(() =>
         compile(`<script setup>
         let bar = 1
-        defineModel({
+        const model = defineModel({
           get: () => bar,
           set: () => bar
         })

packages/compiler-sfc/__tests__/compileScript/defineModel.spec.ts

@@ -269,4 +269,16 @@ describe('defineModel()', () => {
       modelValue: BindingTypes.SETUP_REF,
     })
   })
+
+  test('error when defineModel is not assigned to a variable', () => {
+    expect(() =>
+      compile(`
+        <script setup>
+        defineModel()
+        </script>
+      `),
+    ).toThrow(
+      'defineModel() must be assigned to a variable. For example: const model = defineModel()',
+    )
+  })
 })

packages/compiler-sfc/src/script/defineModel.ts

@@ -22,6 +22,13 @@ export function processDefineModel(
     return false
   }
 
+  if (!declId) {
+    ctx.error(
+      'defineModel() must be assigned to a variable. For example: const model = defineModel()',
+      node,
+    )
+  }
+
   ctx.hasDefineModelCall = true
 
   const type =