Narrow down startAt.fromLivePosition option to only apply on live stream

doc/api/Loading_a_Content.md

@@ -191,13 +191,12 @@ either:
   - for VoD contents, it is the difference between the starting position and the end
     position of the content.
 
-- **fromLivePosition** relative position relative to the content's live edge (for live
-  contents, it is the position that is intended to be broadcasted at the current time) if
-  it makes sense, in seconds. Should be a negative number.
+- **fromLivePosition** position relative to the content's live edge (i.e. the position
+  that is intended to be broadcast at the current time) if it makes sense, in seconds.
+  Should be a negative number.
 
   If the live edge is unknown or if it does not make sense for the current content (for
-  example, it won't make sense for a VoD content), that setting repeats the same behavior
-  than **fromLastPosition**.
+  example, it won't make sense for VoD content), this setting is ignored.
 
 - **percentage** (`Number`): percentage of the wanted position. `0` being the minimum
   position possible (0 for static content, buffer depth for dynamic contents) and `100`

src/main_thread/init/utils/get_initial_time.ts

@@ -93,6 +93,8 @@ export default function getInitialTime(
   if (!isNullOrUndefined(startAt)) {
     const min = getMinimumSafePosition(manifest);
     const max = getMaximumSafePosition(manifest);
+    const livePosition = getLivePosition(manifest);
+
     if (!isNullOrUndefined(startAt.position)) {
       log.debug("Init: using startAt.minimumPosition");
       return Math.max(Math.min(startAt.position, max), min);
@@ -110,9 +112,12 @@ export default function getInitialTime(
       log.debug("Init: using startAt.fromLastPosition");
       const { fromLastPosition } = startAt;
       return fromLastPosition >= 0 ? max : Math.max(min, max + fromLastPosition);
-    } else if (!isNullOrUndefined(startAt.fromLivePosition)) {
+    } else if (
+      !isNullOrUndefined(startAt.fromLivePosition) &&
+      livePosition !== undefined &&
+      manifest.isLive
+    ) {
       log.debug("Init: using startAt.fromLivePosition");
-      const livePosition = getLivePosition(manifest) ?? max;
       const { fromLivePosition } = startAt;
       return fromLivePosition >= 0
         ? livePosition