feat(typeEvaluator): validate if arg to sanity::versionOf is string

src/typeEvaluator/functions.ts

@@ -1,3 +1,4 @@
+/* eslint-disable max-statements */
 import type {FuncCallNode} from '../nodeTypes'
 import {Scope} from './scope'
 import {walk} from './typeEvaluate'
@@ -297,7 +298,13 @@ export function handleFuncCallNode(node: FuncCallNode, scope: Scope): TypeNode {
       })
     }
     case 'sanity.versionOf': {
-      return {type: 'array', of: {type: 'string'}}
+      const typeNode = walk({node: node.args[0], scope})
+      return mapConcrete(typeNode, scope, (typeNode) => {
+        if (typeNode.type !== 'string') {
+          return {type: 'null'}
+        }
+        return {type: 'array', of: {type: 'string'}}
+      })
     }
     default: {
       return {type: 'unknown'}