Fixed #218, checking for list types on spread operators.

src/locale/en-US.json

@@ -413,7 +413,7 @@
                     "secondary": "I have has the same name as $1"
                 },
                 "IncompatibleType": {
-                    "primary": "I'm supposed to be $2, but I'm $1",
+                    "primary": "I'm supposed to be a $2, but I'm a $1",
                     "secondary": "Oh… sorry, a $1, really?"
                 },
                 "MisplacedShare": "I can only share things at the @Program level, not inside anything!",

src/nodes/ListLiteral.test.ts

@@ -0,0 +1,11 @@
+import { test } from 'vitest';
+import { testConflict } from '@conflicts/TestUtilities';
+import IncompatibleType from '../conflicts/IncompatibleType';
+import Spread from './Spread';
+
+test.each([['num: [1] [1 :num]', 'num: 2 [1 :num]', Spread, IncompatibleType]])(
+    'Expect %s no conflicts, %s to have %s with %s',
+    (good, bad, node, conflict) => {
+        testConflict(good, bad, node, conflict);
+    }
+);

src/nodes/Spread.ts

@@ -10,6 +10,9 @@ import { BIND_SYMBOL } from '../parser/Symbols';
 import AnyType from './AnyType';
 import ListType from './ListType';
 import type Locales from '../locale/Locales';
+import type Context from './Context';
+import IncompatibleType from '../conflicts/IncompatibleType';
+import type Conflict from '../conflicts/Conflict';
 
 /** Inside a list literal, flattens values of a list value into a new list */
 export default class Spread extends Node {
@@ -63,8 +66,21 @@ export default class Spread extends Node {
         return 'list';
     }
 
-    computeConflicts() {
-        return;
+    computeConflicts(context: Context): Conflict[] {
+        if (this.list) {
+            const type = this.list.getType(context);
+            if (!(type instanceof ListType))
+                return [
+                    new IncompatibleType(
+                        this,
+                        ListType.make(),
+                        this.list,
+                        type
+                    ),
+                ];
+        }
+
+        return [];
     }
 
     getNodeLocale(locales: Locales) {