fix(vitest): show error when calling API on files that user has no ac…

…cess to (#4085)

packages/ui/client/components/views/ViewReport.vue

@@ -35,7 +35,7 @@ function escapeHtml(unsafe: string) {
 
 function createHtmlError(filter: Convert, error: ErrorWithDiff) {
   let htmlError = ''
-  if (error.message.includes('\x1B'))
+  if (error.message?.includes('\x1B'))
     htmlError = `<b>${error.nameStr || error.name}</b>: ${filter.toHtml(escapeHtml(error.message))}`
 
   const startStrWithX1B = error.stackStr?.includes('\x1B')

packages/vitest/src/api/setup.ts

@@ -80,20 +80,19 @@ export function setup(vitestOrWorkspace: Vitest | WorkspaceProject, server?: Vit
           return fs.readFile(id, 'utf-8')
         },
         async saveTestFile(id, content) {
-          // can save only already existing test file
           if (!ctx.state.filesMap.has(id) || !existsSync(id))
-            return
+            throw new Error(`Test file "${id}" was not registered, so it cannot be updated using the API.`)
           return fs.writeFile(id, content, 'utf-8')
         },
         async saveSnapshotFile(id, content) {
           if (!ctx.snapshot.resolvedPaths.has(id))
-            return
+            throw new Error(`Snapshot file "${id}" does not exist.`)
           await fs.mkdir(dirname(id), { recursive: true })
           return fs.writeFile(id, content, 'utf-8')
         },
         async removeSnapshotFile(id) {
           if (!ctx.snapshot.resolvedPaths.has(id) || !existsSync(id))
-            return
+            throw new Error(`Snapshot file "${id}" does not exist.`)
           return fs.unlink(id)
         },
         snapshotSaved(snapshot) {