Comment that cache-filling should be no-fail (we don't use it anyway)

src/blockfile/SimpleBlockFile.cpp

@@ -267,6 +267,8 @@ bool SimpleBlockFile::WriteSimpleBlockFile(
    return true;
 }
 
+// This function should try to fill the cache, but just return without effect
+// (not throwing) if there is failure.
 void SimpleBlockFile::FillCache()
 {
    if (mCache.active)

src/blockfile/SimpleBlockFile.h

@@ -82,7 +82,8 @@ class PROFILE_DLL_API SimpleBlockFile /* not final */ : public BlockFile {
    void WriteCacheToDisk() override;
 
    bool GetNeedFillCache() override { return !mCache.active; }
-   void FillCache() override;
+
+   void FillCache() /* noexcept */ override;
 
  protected: