fix another crash that can occur during loading of a ui5 site

Author: DetachHead

src/browser/common.ts

@@ -32,7 +32,8 @@ declare global {
  * handling for if the page is not ui5.
  * sap webgui also uses a global sap object so we need to check for sap.ui specifically
  */
-export const isUi5 = () => typeof sap !== 'undefined' && typeof sap.ui !== 'undefined'
+// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition -- the types don't account for this but any of these could be undefined if the ui5 runtime is partially loaded
+export const isUi5 = () => typeof sap !== 'undefined' && sap.ui?.core !== undefined
 
 export class Ui5SelectorEngineError extends Error {
     constructor(selector: string, error: unknown) {

src/browser/css.ts

@@ -61,8 +61,8 @@ const querySelector = (root: Element | Document, selector: AstSelector): Element
         }
 
         const controls =
-            // eslint-disable-next-line detachhead/suggestions-as-errors, @typescript-eslint/no-unnecessary-condition -- using the deprecated registry since we still want to support older ui5 versions, seems this can be undefined if the page is in the middle of loading
-            sap.ui.core.Element?.registry.filter((element) => {
+            // eslint-disable-next-line detachhead/suggestions-as-errors, @typescript-eslint/no-unnecessary-condition -- using the deprecated registry since we still want to support older ui5 versions, seems any part of this can be undefined if the page is in the middle of loading
+            sap.ui?.core?.Element?.registry.filter((element) => {
                 if (
                     (rule.tag?.type === 'TagName' &&
                         rule.tag.name !== element.getMetadata().getName() &&

tests/css.spec.ts

@@ -142,6 +142,15 @@ test.describe('no ui5 site', () => {
             })
             await expect(page.locator('ui5_css=m.Button')).toHaveCount(0)
         })
+        test('ui5 runtime is partially loaded', async ({ page }) => {
+            await page.evaluate(() => {
+                // @ts-expect-error https://github.com/microsoft/TypeScript/issues/43434
+                window.sap = {
+                    ui: {},
+                }
+            })
+            await expect(page.locator('ui5_css=m.Button')).toHaveCount(0)
+        })
     })
     test.describe('unsupported syntax', () => {
         test('comparitors', ({ page }) =>