refactor: clean up unused catch variables

frontend/src/components/editor/ComposeCanvas.tsx

@@ -122,7 +122,7 @@ export function ComposeCanvas({
   // re-calculates height based on content and applies the zoom transform
   const syncViewport = useCallback(() => {
     if (!(fabricRef.current && wrapperRef.current)) return;
-    textboxRef.current.initDimensions();
+    textboxRef.current?.initDimensions();
 
     const minHeight = initialData?.canvasHeight ?? DEFAULT_LOGICAL_HEIGHT;
     logicalSizeRef.current.height = measureLogicalContentHeight(

frontend/src/components/editor/PostSealModal.tsx

@@ -63,7 +63,11 @@ export function PostSealModal({
               type="button"
               data-testid="view-letter-btn"
               className="btn btn-primary btn-sm"
-              onClick={() => navigate(PATHS.read(sealedTargetId!))}
+              onClick={() => {
+                if (sealedTargetId) {
+                  navigate(PATHS.read(sealedTargetId));
+                }
+              }}
             >
               View letter
             </button>