emulate geolocation POSITION_UNAVAILABLE error

index.bs

@@ -182,6 +182,8 @@ spec: GEOMETRY; urlPrefix: https://drafts.fxtf.org/geometry/
     text: height dimension; url: rectangle-height-dimension
 spec: GEOLOCATION; urlPrefix: https://www.w3.org/TR/geolocation/
   type: dfn
+    text: GeolocationPositionError; url: #dom-geolocationpositionerror
+    text: POSITION_UNAVAILABLE; url: #dom-geolocationpositionerror-position_unavailable
     text: set emulated position data; url: #dfn-set-emulated-position-data
 spec: HTML; urlPrefix: https://html.spec.whatwg.org/multipage/
   type: dfn
@@ -5623,7 +5625,10 @@ The <dfn export for=commands>emulation.setGeolocationOverride</dfn> command modi
       )
 
       emulation.SetGeolocationOverrideParameters = {
-        coordinates: emulation.GeolocationCoordinates / null,
+        (
+          (coordinates: emulation.GeolocationCoordinates / null) //
+          (error: emulation.GeolocationPositionError)
+        ),
         ? contexts: [+browsingContext.BrowsingContext],
         ? userContexts: [+browser.UserContext],
       }
@@ -5637,6 +5642,10 @@ The <dfn export for=commands>emulation.setGeolocationOverride</dfn> command modi
          ? heading: (0.0...360.0) / null .default null,
          ? speed: (float .ge 0.0) / null .default null,
       }
+
+      emulation.GeolocationPositionError = {
+         type: "positionUnavailable"
+      }
     </pre>
    </dd>
    <dt>Result Type</dt>
@@ -5651,9 +5660,26 @@ The <dfn export for=commands>emulation.setGeolocationOverride</dfn> command modi
 
 The [=remote end steps=] with |command parameters| are:
 
-1. If |command parameters| [=map/contains=] "<code>altitudeAccuracy</code>"
-   and |command parameters| doesn't [=map/contain=] "<code>altitude</code>",
-   return [=error=] with [=error code=] [=invalid argument=].
+1. If |command parameters| [=map/contains=] "<code>coordinates</code>" and
+   |command parameters|["<code>coordinates</code>"] [=map/contains=]
+   "<code>altitudeAccuracy</code>" and
+   |command parameters|["<code>coordinates</code>"] doesn't [=map/contain=]
+   "<code>altitude</code>", return [=error=] with [=error code=]
+   [=invalid argument=].
+
+1. If |command parameters| [=map/contains=] "<code>error</code>":
+
+   1. Assert |command parameters|["<code>error</code>"]["<code>type</code>"] equals
+      "<code>positionUnavailable</code>".
+
+   1. Let |emulated position data| be a [=/map=] matching [=GeolocationPositionError=]
+      production, with <code>code</code> field set to [=POSITION_UNAVAILABLE=] and
+      <code>message</code> field set to the empty string.
+
+      Note: <code>message</code> will be ignored by implementation according to the geolocation spec.
+
+1. Otherwise, let |emulated position data| be
+   |command parameters|["<code>coordinates</code>"].
 
 1. If |command parameters| [=map/contains=] "<code>userContexts</code>"
    and |command parameters| [=map/contains=] "<code>context</code>",
@@ -5675,7 +5701,7 @@ The [=remote end steps=] with |command parameters| are:
 
    1. For each |user context| of |user contexts|:
 
-      1. [=map/Set=] [=geolocation overrides map=][|user context|] to |command parameters|["<code>coordinates</code>"].
+      1. [=map/Set=] [=geolocation overrides map=][|user context|] to |emulated position data|.
 
       1. [=list/For each=] |top-level traversable| of the list of all [=/top-level traversables=]
          whose [=associated user context=] is |user context|:
@@ -5684,7 +5710,7 @@ The [=remote end steps=] with |command parameters| are:
 
 1. For each |navigable| of |navigables|:
 
-   1. [=Set emulated position data=] with |navigable| and |command parameters|["<code>coordinates</code>"].
+   1. [=Set emulated position data=] with |navigable| and |emulated position data|.
 
 1. Return [=success=] with data null.