refactor: Refactors throwable errors (#375)

Author: pan-kot

src/board/internal.tsx

@@ -172,10 +172,8 @@ export function InternalBoard<D>({
 
     autoScrollHandlers.stop();
 
-    if (!transition) {
-      throw new Error("Invariant violation: no transition.");
-    }
     if (
+      !transition ||
       !transition.layoutShift ||
       transition.layoutShift.conflicts.length > 0 ||
       transition.layoutShift.moves.length === 0

src/board/transition.ts

@@ -167,12 +167,11 @@ function submitTransition<D>(state: TransitionState<D>): TransitionState<D> {
   }
 
   if (!transition) {
-    throw new Error("Invariant violation: no transition.");
+    return { transition: null, removeTransition: null, announcement: null };
   }
 
   const { operation, itemsLayout, draggableItem: item, acquiredItem } = transition;
   const itemBelongsToBoard = item.id === acquiredItem?.id || itemsLayout.items.some((it) => it.id === item.id);
-
   return transition.layoutShift?.conflicts.length === 0
     ? {
         transition: null,
@@ -190,16 +189,15 @@ function discardTransition<D>(state: TransitionState<D>): TransitionState<D> {
   const { transition, removeTransition } = state;
 
   if (removeTransition) {
-    throw new Error("Can't discard remove transition.");
+    throw new Error("Invariant violation: can't discard remove transition.");
   }
 
   if (!transition) {
-    throw new Error("Invariant violation: no transition.");
+    return { transition: null, removeTransition: null, announcement: null };
   }
 
   const { operation, itemsLayout, draggableItem: item, acquiredItem } = transition;
   const itemBelongsToBoard = item.id === acquiredItem?.id || itemsLayout.items.some((it) => it.id === item.id);
-
   return {
     transition: null,
     removeTransition: null,
@@ -214,7 +212,7 @@ function updateTransitionWithPointerEvent<D>(
   const { transition } = state;
 
   if (!transition) {
-    throw new Error("Invariant violation: no transition.");
+    return { transition: null, removeTransition: null, announcement: null };
   }
 
   const layout = transition.layoutShift?.next ?? transition.itemsLayout;
@@ -270,7 +268,7 @@ function updateTransitionWithKeyboardEvent<D>(
   const { transition } = state;
 
   if (!transition) {
-    throw new Error("Invariant violation: no transition.");
+    return { transition: null, removeTransition: null, announcement: null };
   }
 
   const updateManualItemTransition = (transition: Transition<D>, direction: Direction): TransitionState<D> => {
@@ -326,7 +324,7 @@ function acquireTransitionItem<D>(
   const { transition } = state;
 
   if (!transition) {
-    throw new Error("Invariant violation: no transition.");
+    return { transition: null, removeTransition: null, announcement: null };
   }
 
   const { columns } = transition.itemsLayout;

src/board/utils/__tests__/path.test.ts

@@ -92,7 +92,7 @@ describe("appendMovePath", () => {
   test("throws if can't find incremental path within 100 steps", () => {
     const path = [new Position({ x: 0, y: 0 })];
     const rect = { left: 0, right: 1, top: 100, bottom: 101 };
-    expect(() => appendMovePath(path, rect)).toThrow("Infinite loop in appendPath.");
+    expect(() => appendMovePath(path, rect)).toThrow("Invariant violation: infinite loop in appendPath.");
   });
 });
 

src/board/utils/path.ts

@@ -76,7 +76,7 @@ function appendPath(prevPath: readonly Position[], nextPosition: Position): Posi
 
   while (x !== nextPosition.x || y !== nextPosition.y) {
     if (++safetyCounter === 100) {
-      throw new Error("Infinite loop in appendPath.");
+      throw new Error("Invariant violation: infinite loop in appendPath.");
     }
     if (x !== nextPosition.x) {
       x += vx;

src/internal/dnd-controller/controller.ts

@@ -74,14 +74,16 @@ class DragAndDropController extends EventEmitter<DragAndDropEvents> {
    */
   public start(transition: Transition) {
     this.transition = { ...transition };
-    this.emit("start", this.getDragAndDropData(transition.startCoordinates));
+    this.emit("start", this.getDragAndDropData(transition, transition.startCoordinates));
   }
 
   /**
    * Updates current transition with given coordinates and issues an "update" event.
    */
   public update(coordinates: Coordinates) {
-    this.emit("update", this.getDragAndDropData(coordinates));
+    if (this.transition) {
+      this.emit("update", this.getDragAndDropData(this.transition, coordinates));
+    }
   }
 
   /**
@@ -104,10 +106,9 @@ class DragAndDropController extends EventEmitter<DragAndDropEvents> {
    * Issues an "acquire" event to notify the current transition draggable is acquired by the given droppable.
    */
   public acquire(droppableId: ItemId, renderAcquiredItem: () => ReactNode) {
-    if (!this.transition) {
-      throw new Error("Invariant violation: no transition present for acquire.");
+    if (this.transition) {
+      this.emit("acquire", { droppableId, draggableItem: this.transition.draggableItem, renderAcquiredItem });
     }
-    this.emit("acquire", { droppableId, draggableItem: this.transition.draggableItem, renderAcquiredItem });
   }
 
   /**
@@ -131,14 +132,11 @@ class DragAndDropController extends EventEmitter<DragAndDropEvents> {
     return [...this.droppables.entries()];
   }
 
-  private getDragAndDropData(coordinates: Coordinates): DragAndDropData {
-    if (!this.transition) {
-      throw new Error("Invariant violation: no transition present for interaction.");
-    }
-    const positionOffset = Coordinates.cursorOffset(coordinates, this.transition.startCoordinates);
-    const collisionRect = this.getCollisionRect(this.transition, coordinates);
+  private getDragAndDropData(transition: Transition, coordinates: Coordinates): DragAndDropData {
+    const positionOffset = Coordinates.cursorOffset(coordinates, transition.startCoordinates);
+    const collisionRect = this.getCollisionRect(transition, coordinates);
     const { collisionIds, dropTarget } = this.getCollisions(collisionRect);
-    return { ...this.transition, positionOffset, coordinates, collisionRect, collisionIds, dropTarget };
+    return { ...transition, positionOffset, coordinates, collisionRect, collisionIds, dropTarget };
   }
 
   private getCollisionRect(transition: Transition, coordinates: Coordinates) {
@@ -154,7 +152,6 @@ class DragAndDropController extends EventEmitter<DragAndDropEvents> {
     if (collisionIds.length === 0) {
       return { collisionIds, dropTarget: null };
     }
-
     const matchedDroppable = droppableEntries.find(([id]) => id === collisionIds[0]);
     if (!matchedDroppable) {
       throw new Error("Invariant violation: no droppable matches collision.");

src/internal/global-drag-state-styles/index.ts

@@ -4,10 +4,6 @@ import { DragAndDropData, useDragSubscription } from "../dnd-controller/controll
 
 import styles from "./styles.css.js";
 
-function assertNever(value: never) {
-  throw new Error("Unexpected value: " + value);
-}
-
 function setup({ operation, interactionType }: DragAndDropData) {
   const isPointerInteraction = interactionType === "pointer";
   switch (operation) {
@@ -23,8 +19,7 @@ function setup({ operation, interactionType }: DragAndDropData) {
       }
       break;
     default:
-      // there will be a type error if not all operation types are handled
-      assertNever(operation);
+      throw new Error("Invariant violation: unexpected operation type.");
   }
 
   if (isPointerInteraction) {

src/internal/item-container/index.tsx

@@ -129,7 +129,7 @@ export const ItemContext = createContext<ItemContextType | null>(null);
 export function useItemContext() {
   const ctx = useContext(ItemContext);
   if (!ctx) {
-    throw new Error("Unable to find BoardItem context.");
+    throw new Error("Invariant violation: no board item context.");
   }
   return ctx;
 }

src/internal/utils/layout.ts

@@ -88,7 +88,7 @@ export function transformItems<D>(
   const getItem = (itemId: ItemId) => {
     const item = itemById.get(itemId);
     if (!item) {
-      throw new Error("Invariant violation: no matching source item found.");
+      throw new Error("Invariant violation: no layout item matches given id.");
     }
     return item;
   };

src/items-palette/internal.tsx

@@ -90,7 +90,7 @@ export function InternalItemsPalette<D>({
               inTransition={false}
               getItemSize={(dropContext) => {
                 if (!dropContext) {
-                  throw new Error("Invariant violation: cannot query palette item size with no drop context.");
+                  throw new Error("Invariant violation: no drop context in palette.");
                 }
                 const { width, height } = dropContext.scale(item);
                 return { width, minWidth: width, maxWidth: width, height, minHeight: height, maxHeight: height };