fix: small comment, error string, and guard cleanups

- Services JSDoc: "to determine" grapheme clustering wording
- AttributeData: "persistent" spelling in comment
- Buffer.setupTabStops: check only `undefined` (param is `number | undefined`)
- SerializeAddon: fix "we must" and duplicate "the" in comment
- WebglAddon: use "WebGL2" in Safari support error for consistency
- TextureAtlas: "relevant" spelling in comment

Co-authored-by: Cursor <cursoragent@cursor.com>

src/common/buffer/AttributeData.ts

@@ -204,7 +204,7 @@ export class ExtendedAttrs implements IExtendedAttrs {
 
   /**
    * Convenient method to indicate whether the object holds no additional information,
-   * that needs to be persistant in the buffer.
+   * that needs to be persistent in the buffer.
    */
   public isEmpty(): boolean {
     return this.underlineStyle === UnderlineStyle.NONE && this._urlId === 0;