Spec: minor fixes

Fixes some minor issues discovered in the spec, also adds some Issue
comments to track some potential future clean ups.

spec.bs

@@ -125,7 +125,7 @@ Exposed interface {#exposed-interface}
  SecureContext]
 interface PrivateAggregation {
   undefined contributeToHistogram(PAHistogramContribution contribution);
-  undefined enableDebugMode(optional PADebugModeOptions options = {});
+  undefined enableDebugMode(optional PADebugModeOptions options);
 };
 
 dictionary PAHistogramContribution {
@@ -138,6 +138,10 @@ dictionary PADebugModeOptions {
 };
 </xmp>
 
+Issue: Per the <a href=https://www.w3.org/TR/design-principles/#numeric-types>
+  Web Platform Design Principles</a>, we should consider switching `long` to
+  `[EnforceRange] long long`.
+
 Each {{PrivateAggregation}} object has the following fields:
 <dl dfn-for="PrivateAggregation">
 : <dfn>scoping details</dfn> (default null)
@@ -1294,12 +1298,23 @@ event, PAExtendedHistogramContribution contribution)</dfn> method steps are:
         value=], [=exception/throw=] a {{TypeError}}.
     1. If |bucket|["{{PASignalValue/offset}}"] is not a {{bigint}}, [=exception/
         throw=] a {{TypeError}}.
+1. Otherwise, if |contribution|["{{PAExtendedHistogramContribution/bucket}}"] is
+    not in the range [0, 2<sup>128</sup>−1], [=exception/throw=] a
+    {{TypeError}}.
+
+    Issue: Make the error type consistent with
+        {{PrivateAggregation/contributeToHistogram(contribution)}}.
 1. Let |value| be |contribution|["{{PAExtendedHistogramContribution/value}}"].
 1. If |value| is a {{PASignalValue}}:
     1. If |value|["{{PASignalValue/baseValue}}"] is not a valid [=signal base
         value=], [=exception/throw=] a {{TypeError}}.
     1. If |value|["{{PASignalValue/offset}}"] is a {{bigint}}, [=exception/
         throw=] a {{TypeError}}.
+1. Otherwise, if |contribution|["{{PAHistogramContribution/value}}"] is
+    negative, [=exception/throw=] a {{TypeError}}.
+
+    Issue: Make the error types on validation issues here and above consistent
+        with {{PrivateAggregation/contributeToHistogram(contribution)}}.
 1. Let |batchingScope| be null.
 1. If |event| [=string/starts with=] "`reserved.`", set |batchingScope| to the
     result of running |scopingDetails|' [=scoping details/get batching scope
@@ -1973,10 +1988,10 @@ To <dfn>fill in the contribution</dfn> given a
 following steps. They return a {{PAHistogramContribution}}.
 1. Let |bucket| be |contribution|["{{PAExtendedHistogramContribution/bucket}}"].
 1. If |bucket| is a {{PASignalValue}}, set |bucket| to the result of [=filling
-    in the signal value=] given |bucket|, 65535 and |leadingBidInfo|.
+    in the signal value=] given |bucket|, 2<sup>128</sup>−1 and |leadingBidInfo|.
 1. Let |value| be |contribution|["{{PAExtendedHistogramContribution/value}}"].
 1. If |value| is a {{PASignalValue}}, set |value| to the result of [=filling in
-    the signal value=] given |value|, 2<sup>128</sup>−1 and |leadingBidInfo|.
+    the signal value=] given |value|, 65535 and |leadingBidInfo|.
 1. Return a new {{PAHistogramContribution}} with the items:
     : {{PAHistogramContribution/bucket}}
     :: |bucket|