2 files changed, 8 insertions, 6 deletions
diff --git a/components/script/dom/offscreencanvas.rs b/components/script/dom/offscreencanvas.rs
index d820149a7b0..2be33688afc 100644
--- a/components/script/dom/offscreencanvas.rs
+++ b/components/script/dom/offscreencanvas.rs
@@ -15,7 +15,7 @@ use crate::dom::bindings::cell::{ref_filter_map, DomRefCell, Ref};
 use crate::dom::bindings::codegen::Bindings::OffscreenCanvasBinding::{
     OffscreenCanvasMethods, OffscreenRenderingContext,
 };
-use crate::dom::bindings::error::Fallible;
+use crate::dom::bindings::error::{Error, Fallible};
 use crate::dom::bindings::reflector::{reflect_dom_object_with_proto, DomObject};
 use crate::dom::bindings::root::{Dom, DomRoot};
 use crate::dom::bindings::str::DOMString;
@@ -157,18 +157,20 @@ impl OffscreenCanvasMethods for OffscreenCanvas {
         _cx: JSContext,
         id: DOMString,
         _options: HandleValue,
-    ) -> Option<OffscreenRenderingContext> {
+    ) -> Fallible<Option<OffscreenRenderingContext>> {
         match &*id {
-            "2d" => self
+            "2d" => Ok(self
                 .get_or_init_2d_context()
-                .map(OffscreenRenderingContext::OffscreenCanvasRenderingContext2D),
+                .map(OffscreenRenderingContext::OffscreenCanvasRenderingContext2D)),
             /*"webgl" | "experimental-webgl" => self
                 .get_or_init_webgl_context(cx, options)
                 .map(OffscreenRenderingContext::WebGLRenderingContext),
             "webgl2" | "experimental-webgl2" => self
                 .get_or_init_webgl2_context(cx, options)
                 .map(OffscreenRenderingContext::WebGL2RenderingContext),*/
-            _ => None,
+            _ => Err(Error::Type(String::from(
+                "Unrecognized OffscreenCanvas context type",
+            ))),
         }
     }
 
diff --git a/components/script/dom/webidls/OffscreenCanvas.webidl b/components/script/dom/webidls/OffscreenCanvas.webidl
index 110af8a8f99..04c28f989a5 100644
--- a/components/script/dom/webidls/OffscreenCanvas.webidl
+++ b/components/script/dom/webidls/OffscreenCanvas.webidl
@@ -19,7 +19,7 @@ interface OffscreenCanvas : EventTarget {
   attribute [EnforceRange] unsigned long long width;
   attribute [EnforceRange] unsigned long long height;
 
-  OffscreenRenderingContext? getContext(DOMString contextId, optional any options = null);
+  [Throws] OffscreenRenderingContext? getContext(DOMString contextId, optional any options = null);
   //ImageBitmap transferToImageBitmap();
   //Promise<Blob> convertToBlob(optional ImageEncodeOptions options);
 };