Address review comments

index.bs

@@ -1869,8 +1869,8 @@ usage.
   <tr>
     <td>{{NotReadableError}}</td>
     <td>
-      The operation failed because the file(s) containing the requested
-      data could not be read.
+      The operation failed because the underlying storage containing
+      the requested data could not be read.
     </td>
   </tr>
   <tr>
@@ -1900,7 +1900,7 @@ usage.
     <td>{{UnknownError}}</td>
     <td>
       The operation failed for transient reasons unrelated to the
-      database itself and not covered by any other error.
+      database itself or not covered by any other error.
     </td>
   </tr>
   <tr>
@@ -5643,6 +5643,9 @@ To <dfn>store a record into an object store</dfn> with
 To <dfn>retrieve a value from an object store</dfn> with
 |targetRealm|, |store| and |range|, run these steps:
 
+NOTE:
+    May return a {{DOMException}} if an error occurs while running these steps.
+
 1. Let |record| be the first [=object-store/record=] in |store|'s
     [=object-store/list of records=] whose [=/key=] is [=in=] |range|, if
     any.
@@ -5662,6 +5665,9 @@ To <dfn>retrieve a value from an object store</dfn> with
 To <dfn>retrieve multiple values from an object
 store</dfn> with |targetRealm|, |store|, |range| and optional |count|, run these steps:
 
+NOTE:
+    May return a {{DOMException}} if an error occurs while running these steps.
+
 1. If |count| is not given or is 0 (zero), let |count| be infinity.
 
 1. Let |records| be a [=/list=] containing the first |count| [=object-store/records=]