refactor(browser): remove unreachable coords guard in getCoords

getCoordsRelativeToElement always returns a two-element tuple, so the
array is always truthy and if (!coords) could never run. hasValidCharSize
already handles the only early-exit path before coordinates are computed.

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

src/browser/input/Mouse.ts

@@ -37,10 +37,6 @@ export function getCoords(window: Pick<Window, 'getComputedStyle'>, event: Pick<
   }
 
   const coords = getCoordsRelativeToElement(window, event, element);
-  if (!coords) {
-    return undefined;
-  }
-
   coords[0] = Math.ceil((coords[0] + (isSelection ? cssCellWidth / 2 : 0)) / cssCellWidth);
   coords[1] = Math.ceil(coords[1] / cssCellHeight);