diff --git a/spine-ts/spine-core/src/AtlasAttachmentLoader.ts b/spine-ts/spine-core/src/AtlasAttachmentLoader.ts
index 3d0d53de0..db1b0c9f6 100644
--- a/spine-ts/spine-core/src/AtlasAttachmentLoader.ts
+++ b/spine-ts/spine-core/src/AtlasAttachmentLoader.ts
@@ -27,16 +27,16 @@
  * THE SPINE RUNTIMES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *****************************************************************************/
 
-import { AttachmentLoader } from "./attachments/AttachmentLoader.js";
+import type { AttachmentLoader } from "./attachments/AttachmentLoader.js";
 import { BoundingBoxAttachment } from "./attachments/BoundingBoxAttachment.js";
 import { ClippingAttachment } from "./attachments/ClippingAttachment.js";
 import { MeshAttachment } from "./attachments/MeshAttachment.js";
 import { PathAttachment } from "./attachments/PathAttachment.js";
 import { PointAttachment } from "./attachments/PointAttachment.js";
 import { RegionAttachment } from "./attachments/RegionAttachment.js";
-import { Skin } from "./Skin.js";
-import { TextureAtlas } from "./TextureAtlas.js";
-import { Sequence } from "./attachments/Sequence.js"
+import type { Sequence } from "./attachments/Sequence.js"
+import type { Skin } from "./Skin.js";
+import type { TextureAtlas } from "./TextureAtlas.js";
 
 /** An {@link AttachmentLoader} that configures attachments using texture regions from an {@link TextureAtlas}.
  *
@@ -44,40 +44,44 @@ import { Sequence } from "./attachments/Sequence.js"
  * Spine Runtimes Guide. */
 export class AtlasAttachmentLoader implements AttachmentLoader {
 	atlas: TextureAtlas;
+	allowMissingRegions: boolean;
 
-	constructor (atlas: TextureAtlas) {
+	constructor (atlas: TextureAtlas, allowMissingRegions = false) {
 		this.atlas = atlas;
+		this.allowMissingRegions = allowMissingRegions;
 	}
 
 	loadSequence (name: string, basePath: string, sequence: Sequence) {
-		let regions = sequence.regions;
+		const regions = sequence.regions;
 		for (let i = 0, n = regions.length; i < n; i++) {
-			let path = sequence.getPath(basePath, i);
-			let region = this.atlas.findRegion(path);
-			if (region == null) throw new Error("Region not found in atlas: " + path + " (sequence: " + name + ")");
-			regions[i] = region;
+			const path = sequence.getPath(basePath, i);
+			regions[i] = this.atlas.findRegion(path);
+			if (regions[i] == null && !this.allowMissingRegions)
+				throw new Error(`Region not found in atlas: ${path} (sequence: ${name})`);
 		}
 	}
 
 	newRegionAttachment (skin: Skin, name: string, path: string, sequence: Sequence): RegionAttachment {
-		let attachment = new RegionAttachment(name, path);
+		const attachment = new RegionAttachment(name, path);
 		if (sequence != null) {
 			this.loadSequence(name, path, sequence);
 		} else {
-			let region = this.atlas.findRegion(path);
-			if (!region) throw new Error("Region not found in atlas: " + path + " (region attachment: " + name + ")");
+			const region = this.atlas.findRegion(path);
+			if (region == null && !this.allowMissingRegions)
+				throw new Error(`Region not found in atlas: ${path} (region attachment: ${name})`);
 			attachment.region = region;
 		}
 		return attachment;
 	}
 
 	newMeshAttachment (skin: Skin, name: string, path: string, sequence: Sequence): MeshAttachment {
-		let attachment = new MeshAttachment(name, path);
+		const attachment = new MeshAttachment(name, path);
 		if (sequence != null) {
 			this.loadSequence(name, path, sequence);
 		} else {
-			let region = this.atlas.findRegion(path);
-			if (!region) throw new Error("Region not found in atlas: " + path + " (mesh attachment: " + name + ")");
+			const region = this.atlas.findRegion(path);
+			if (region == null && !this.allowMissingRegions)
+				throw new Error(`Region not found in atlas: ${path} (mesh attachment: ${name})`);
 			attachment.region = region;
 		}
 		return attachment;
diff --git a/spine-ts/spine-core/src/SkeletonBinary.ts b/spine-ts/spine-core/src/SkeletonBinary.ts
index 235852355..1e4228a5c 100644
--- a/spine-ts/spine-core/src/SkeletonBinary.ts
+++ b/spine-ts/spine-core/src/SkeletonBinary.ts
@@ -27,8 +27,8 @@
  * THE SPINE RUNTIMES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *****************************************************************************/
 
-import { Animation, Timeline, InheritTimeline, AttachmentTimeline, RGBATimeline, RGBTimeline, RGBA2Timeline, RGB2Timeline, AlphaTimeline, RotateTimeline, TranslateTimeline, TranslateXTimeline, TranslateYTimeline, ScaleTimeline, ScaleXTimeline, ScaleYTimeline, ShearTimeline, ShearXTimeline, ShearYTimeline, IkConstraintTimeline, TransformConstraintTimeline, PathConstraintPositionTimeline, PathConstraintSpacingTimeline, PathConstraintMixTimeline, DeformTimeline, DrawOrderTimeline, EventTimeline, CurveTimeline1, CurveTimeline, SequenceTimeline, PhysicsConstraintResetTimeline, PhysicsConstraintInertiaTimeline, PhysicsConstraintStrengthTimeline, PhysicsConstraintDampingTimeline, PhysicsConstraintMassTimeline, PhysicsConstraintWindTimeline, PhysicsConstraintGravityTimeline, PhysicsConstraintMixTimeline, BoneTimeline2, SliderTimeline, SliderMixTimeline } from "./Animation.js";
-import { VertexAttachment, Attachment } from "./attachments/Attachment.js";
+import { AlphaTimeline, Animation, AttachmentTimeline, BoneTimeline2, CurveTimeline, CurveTimeline1, DeformTimeline, DrawOrderTimeline, EventTimeline, IkConstraintTimeline, InheritTimeline, PathConstraintMixTimeline, PathConstraintPositionTimeline, PathConstraintSpacingTimeline, PhysicsConstraintDampingTimeline, PhysicsConstraintGravityTimeline, PhysicsConstraintInertiaTimeline, PhysicsConstraintMassTimeline, PhysicsConstraintMixTimeline, PhysicsConstraintResetTimeline, PhysicsConstraintStrengthTimeline, PhysicsConstraintWindTimeline, RGB2Timeline, RGBA2Timeline, RGBATimeline, RGBTimeline, RotateTimeline, ScaleTimeline, ScaleXTimeline, ScaleYTimeline, SequenceTimeline, ShearTimeline, ShearXTimeline, ShearYTimeline, SliderMixTimeline, SliderTimeline, Timeline, TransformConstraintTimeline, TranslateTimeline, TranslateXTimeline, TranslateYTimeline } from "./Animation.js";
+import { Attachment, VertexAttachment } from "./attachments/Attachment.js";
 import { AttachmentLoader } from "./attachments/AttachmentLoader.js";
 import { HasTextureRegion } from "./attachments/HasTextureRegion.js";
 import { MeshAttachment } from "./attachments/MeshAttachment.js";
@@ -488,7 +488,7 @@ export class SkeletonBinary {
 				region.height = height * scale;
 				Color.rgba8888ToColor(region.color, color);
 				region.sequence = sequence;
-				if (sequence == null) region.updateRegion();
+				if (region.region != null) region.updateRegion();
 				return region;
 			}
 			case AttachmentType.BoundingBox: {
@@ -529,7 +529,7 @@ export class SkeletonBinary {
 				mesh.worldVerticesLength = vertices.length;
 				mesh.triangles = triangles;
 				mesh.regionUVs = uvs;
-				if (sequence == null) mesh.updateRegion();
+				if (mesh.region != null) mesh.updateRegion();
 				mesh.hullLength = hullLength << 1;
 				mesh.sequence = sequence;
 				if (nonessential) {
diff --git a/spine-ts/spine-core/src/attachments/Sequence.ts b/spine-ts/spine-core/src/attachments/Sequence.ts
index 6387bd873..b7605eb38 100644
--- a/spine-ts/spine-core/src/attachments/Sequence.ts
+++ b/spine-ts/spine-core/src/attachments/Sequence.ts
@@ -27,17 +27,17 @@
  * THE SPINE RUNTIMES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *****************************************************************************/
 
-import { TextureRegion } from "../Texture.js";
-import { HasTextureRegion } from "./HasTextureRegion.js";
+import type { SlotPose } from "src/SlotPose.js";
+import type { TextureRegion } from "../Texture.js";
 import { Utils } from "../Utils.js";
-import { SlotPose } from "src/SlotPose.js";
+import type { HasTextureRegion } from "./HasTextureRegion.js";
 
 
 export class Sequence {
 	private static _nextID = 0;
 
 	id = Sequence.nextID();
-	regions: TextureRegion[];
+	regions: Array<TextureRegion | null>;
 	start = 0;
 	digits = 0;
 	/** The index of the region to show for the setup pose. */
@@ -48,7 +48,7 @@ export class Sequence {
 	}
 
 	copy (): Sequence {
-		let copy = new Sequence(this.regions.length);
+		const copy = new Sequence(this.regions.length);
 		Utils.arrayCopy(this.regions, 0, copy.regions, 0, this.regions.length);
 		copy.start = this.start;
 		copy.digits = this.digits;
@@ -58,10 +58,10 @@ export class Sequence {
 
 	apply (slot: SlotPose, attachment: HasTextureRegion) {
 		let index = slot.sequenceIndex;
-		if (index == -1) index = this.setupIndex;
+		if (index === -1) index = this.setupIndex;
 		if (index >= this.regions.length) index = this.regions.length - 1;
-		let region = this.regions[index];
-		if (attachment.region != region) {
+		const region = this.regions[index];
+		if (attachment.region !== region) {
 			attachment.region = region;
 			attachment.updateRegion();
 		}
@@ -69,7 +69,7 @@ export class Sequence {
 
 	getPath (basePath: string, index: number): string {
 		let result = basePath;
-		let frame = (this.start + index).toString();
+		const frame = (this.start + index).toString();
 		for (let i = this.digits - frame.length; i > 0; i--)
 			result += "0";
 		result += frame;