Updates from code review feedback

Author: pmachapman

src/SIL.XForge.Scripture/Services/DeltaUsxMapper.cs

@@ -177,8 +177,8 @@ private static bool CanParaContainVerseText(string? style)
 
     public static string ExtractBookId(string usfm)
     {
-        string firstLine = usfm.Split('\n').FirstOrDefault()?.Trim() ?? string.Empty;
-        return BookIdRegex().Match(firstLine).Groups[1].Value;
+        Match match = BookIdRegex().Match(usfm);
+        return match.Success ? match.Groups[1].Value : string.Empty;
     }
 
     /// <summary>

src/SIL.XForge.Scripture/Services/MachineApiService.cs

@@ -30,6 +30,7 @@
 using Chapter = SIL.XForge.Scripture.Models.Chapter;
 using TextInfo = SIL.XForge.Scripture.Models.TextInfo;
 
+// Disable notice "The logging message template should not vary between calls to..."
 #pragma warning disable CA2254
 
 namespace SIL.XForge.Scripture.Services;
@@ -167,7 +168,9 @@ await hubContext.NotifyDraftApplyProgress(
                     await hubContext.NotifyDraftApplyProgress(sfProjectId, new DraftApplyState { State = message });
                 }
 
-                // Ensure that if chapters is blank, it contains every chapter in the book
+                // Ensure that if chapters is blank, it contains every chapter in the book.
+                // ScriptureRangeParser will return no chapters, meaning all chapters,
+                // if the scripture range just specifies a book without chapter numbers.
                 List<int> chapters = bookChapters;
                 if (chapters.Count == 0)
                 {